Pulmonary Granulomatoses Due to Inhaled Organic Antigens

Pulmonary Granulomatoses Due to Inhaled Organic Antigens JOHN RANKIN, M.D.* MOSABURO KOBAYASHI, M.D. ROBERT A. BARBEE, M.D. HELEN A. DICKIE, M.D.

Numerous granulomatous disorders may produce diffuse or localized pulmonary lesions. Moreover, a similar histologic appearance may be observed in several seemingly unrelated diseases. The list of agents capable of producing epithelioid granulomas (tuberculoid granulomas) has always been a long one, including mycobacteria, fungi, protozoa, beryllium, and zirconium. To this list must now be added several organic dusts of animal or vegetable origin. During the past decade clinical and laboratory investigators have repeatedly demonstrated that a diffuse granulomatous pneumonitis may result from the inhalation of organic dusts by persons who have become sensitive to antigens in the dusts. Several seemingly new clinical entities have been described and named according to the source of the dust, the circumstances under which exposure occurs, or the occupation of affected individuals. It now seems reasonably clear, however, that farmer's lung, harvester's lung, thresher's lung, bird breeder's (fancier's) lung, pigeon breeder's lung, maple bark disease, bagassosis, sequoiosis, and possibly several other entities described recently are all clinical expressions of the same basic mechanism of disease. In practically every instance studied, the serum of affected individuals has been shown to contain high titers of precipitating antibodies against antigens present in the dusts encountered (Table 1). Studies conducted by us over the past 12 years l • 5. 15. 16. 25. 26. 27. 31 From the Department of Medicine, University of Wisconsin School of Medicine, University Hospitals, Madison, Wisconsin. This study was supported by a grant (OH 00044) from the Division of Environmental Health, U .S. Public Health Service 'Oscar Rennebohm Professor of Medicine

Medical Clinics of North America- Vo!. 51, No. 2, March, 1967

459

460

J. RANKIN, M. KOBAYASHI, R. A. BARBEE, H. A. DICKIE

Table 1.

Organic Dust Exposure Causing Acute Granulomatous Interstitial Pneumonitis

DISEASE

SOURCE OF DUST

SPECIFIC ANTIGEN

Farmer's lung Thresher's lung Harvester's lung Fog fever in cattle

Moldy hay, straw, silage, millet, oats, corn, barley, tobacco, or beet pulp

Thermophilic actinomycetes including T. polyspora and M. vulgaris

Mushroom worker's disease

Compost used for growing mushrooms

Not yet identified; probably thermophilic actinomycetes

Bagassosis

Moldy residue of sugar cane (bagasse)

Not yet identified; possibly thermophilic actinomycetes

Bird breeder's (fanciers) Avian excreta lung and feathers Pigeon breeder's lung Pigeon flyer's lung

Pigeon or budgerigar serum proteins, and other antigens in their excreta

Sequoiosis

Redwood sawdust (sequoia sempervirens)

Fungus flora

Pituitary snuff

Bovine and porcine proteins

Iatrogenic lung disease

indicate that inhalation of a variety of organic dusts may result in a distinct clinical entity with uniform clinical, roentgenographic, physiologic, pathologic, and immunologic features. For the sake of brevity, and because we have obtained most of our data on agricultural workers, the following refers only to farmer's lung. However, we can show that what is true for this disorder is substantially true for the syndromes seen in bagasse workers, mushroom workers, maple bark strippers, and bird breeders.

CLINICAL FEATURES The characteristic acute syndrome seen in over 100 agricultural workers consisted of chills, fever as high as 106° F., cough, and dyspnea four to eight hours after exposure to a variety of moldy farm dusts (Table 1), and the subsequent development of interstitial pneumonitis. Dyspnea was invariably present and often severe. A harassing cough was common, but the sputum was neither copious nor purulent. Associated with the fever was a generalized malaise and headache. Loss of weight often followed an episode. Abnormal physical findings, except for cyanosis, were confined to the thorax and consisted of fine crepitant rales at the height of full inspiration which were unaccompanied by any physical signs of consolidation or bronchial disease. Provided further exposure was avoided, the acute symptoms usually subsided spontaneously within seven to ten days, but dyspnea often persisted for several

PULMONARY GRANULOMATOSES DUE TO INHALED ORGANIC ANTIGENS

461

months. Prednisone and other anti-inflammatory corticosteroids were effective in controlling the acute symptoms. A polymorphonuclear leukocytosis was frequently found during the acute febrile episode, sometimes associated with a slight transient eosinophilia. The hemoglobin concentration and erythrocyte sedimentation rate were normal. In a relatively small number of patients studied the 7S gamma globulin fraction of the serum was increased. The roentgenographic features varied according to the duration and severity of the illness. The usual finding was a generalized diffuse interstitial pneumonitis with a very fine pattern of granular or mottled densities, linear striations, and patchy areas of conglomeration. A typical example is seen in Figure 1. Bronchograms failed to reveal any abnormality in the cartilaginous bronchi. A characteristic roentgenogram is almost pathognomonic, but the absence of x-ray abnormality does not exclude a diagnosis of farmer's lung (Fig. 2). The severest episodes usually occurred following the handling of moldy forage in a closed bin, silo, or barn where ventilation was poor. It has been calculated that a farmer working in a barn with a moderately dusty moldy hay retains in his lungs 750,000 spores/min. 17 In Wisconsin, there is a greater chance for the development of farmer's lung than in many areas of the United States. The major farm activity is dairying. This requires the storage of a large amount of hay and grain for cattle feed. Climatic conditions which favor poor drying are common. The hay and grain are usually stored in poorly ventilated mows and bins. Once moldy hay has been in the mow, the area may remain contaminated for years, since the mows are rarely entirely emptied and cleared of the residual moldy material. Severe winters have resulted in the construction of relatively air-tight barns, which cause a higher and more prolonged dust concentration than would be present where feeding is done in the open lot or shed. In addition to these factors, silos are widely used for the production of corn and, more recently, grass silage. This material is frequently moldy on the top and edges when the silo is first opened. The dry, very dusty, moldy silage is tossed down the chute, and frequently the only source of air is from this chute. The dust concentration may be extreme. Frequently the farmer experienced some minor symptoms, such as chills, headache, or malaise, when in contact with the offending dusts prior to the exposure which produced alarming respiratory difficulty. Recurrent episodes of rather serious illness were occasionally observed. More commonly, continued re-exposure resulted in a chronic inflammatory reaction in the lung or numerous subacute episodes of interstitial pneumonitis which ultimately led to chronic irreversible pulmonary insufficiency. These individuals were frequently sick from the time they started to feed stored forage in the fall until the spring, but usually experienced some relief during the summer months. At this stage, fibrotic stringy densities appeared in the chest roentgenograms and cleared slowly, if at all. Eventually, widespread patchy areas of fibrosis,

462

J

RANKIN,

M.

KOBAYASHI,

R. A.

BARBEE,

H. A.

DICKIE

Figure 1. Chest roentgenograms of a 28-year-old farmer who for the first time in December 1959 experienced episodes of chills and fever several hours after handling moldy corncobs. In January 1960 following exposure to the same materials, he developed a fullblown typical attack of farmer's lung. A, film taken about 1 week after onset of illness. B, film taken 3 days later showing significant clearing. C, film taken February 19, 1960 apprOximately 1 week after a second severe attack. There has been a marked increase in the disease. D, film taken approximately 5 weeks after onset of the most recent illness. In the interim there had been no further exposure to moldy farm dusts . The fine granular pattern persisted for several more weeks. (Note Table 3 physiologic abnormalities present at the time of this film.)

accompanied in many by interspersed areas of emphysema, resulted in a roentgenographic piCture indistinguishable from many other forms of diffuse interstitial pulmonary fibrosis.

PULMONARY GRANULOMATOSES DUE TO INHALED ORGANIC ANTIGENS

463

Figure 2. Photomicrograph of lung section of a 32-year-old farmer who experienced a productive cough, fever and dyspnea following exposure to moldy threshing dusts in a poorly ven tilated building in 1952. He recovered and remained well until late December 1954 when he developed an acute interstitial pneumonitis following exposure to moldy bay. He stopped all farm work late in January 1955, but a chest roentgenogram taken 10 days later still showed a fine granular haze in both lung fields. Two months later the chest roentgenogram was reported to be normal, but the following week histologic sections of a biopsy specimen taken from the lingula of the left upper lobe still revealed the characteristic granulomatous interstitial pneumonitis. The alveolar septa are swollen and infiltrated with plasma cells and lymphocytes. Epithelioid cells, Langhan's giant cells and poorly formed tubercles can also be seen. He subsequently sold his farm and has had no recurrence of illness. Reduced from x 145.

PHYSIOLOGIC FEATURES Earl y Features Physiologic studies in acute cases revealed the equally characteristic syndrome of a stiff lung with a reduced diffusing capacity, nonuniform distribution of regional ventilation and blood flow, but no significant change in airway or vascular resistance. The functional derangement correlated directly with the structural alterations seen in lung biopsies. 27 Pulmonary function tests were performed according to accepted standard techniques. The functional derangements typical of this disease are seen in Table 2. The data reported were obtained from the patient whose chest roentgenograms are seen in Figure 1. The first tests coincided with the film taken on March 14, 1960 (Fig. 1, D). At this time a marked reduction in vital capacity due largely to a decrease in inspiratory capacity was seen. This is not surprising in view of the extent of pulmonary infiltration present. Expiratory reserve volume, functional residual capacity and residual volume, and the residual fraction (RV/TLC) were increased.

DIFFUSION AND GAS EXCHANGE Arterial O 2 saturation (%) Arterial CO 2 tension (mm. Hg) Arterial hemoglobin (gm./lOO/ml.) Arterial pH Diffusing capacity of lung

DISTRIBUTION OF INSPIRED GAS N2 after 7 min. oxygen (%) Single breath O 2 - non uniformity of alveolar gas

MECHANICS OF BREATHING Forced expiratory volume in 1 sec (L.) Forced vital capacity (L.) Max. expiratory flow rate (L./min.) Max. inspiratory flow rate (L./min.) Max. voluntary ventilation (L./min.) Lung compliance (L./cm. H 2 O)

LUNG VOLUMES Vital capacity (L.) Inspiratory capacity (L.) Residual volume (L.) Total lung capacity (L.)

96-99 38-44 13.5-15.5 7.38-7.42 33.9

<2.5

4.48 5.12 550 450 152 0.22

4.54 3.63 1.14 5.68

NORMAL

84.2 36.9 17.2 7.41 18.3

2.1

++++

3.08 3.69 382 309 115 0.011

3.67 2.07 2.57 6.29

3/14/60

88.3 38.9 16.8 7.39 21.4

2.0

+++

122

3.17 3.89

3.98 2.79 2.65 6.97

4/21/60

94.7 37.0 15.6 7.44 30.8

0.8

++

4.60 5.94 426 324 146 0.19

5.94 4.29 2.63 8.75

9/21/60

32.1

2.3

+

166

5.03 5.99

5.99 4.26 2.41 8.71

1/27/61

94.5 35.3 16.4 7.46 35.4

4.78 6.18 490 441 175

6.29 4.97 2.12 8.44

2/20/63

Table 2. Early Functional Derangements in a Patient with Farmer's Lung

92.0 37.8 16.4 7.41 38.8

163

4.86

6.29 4.72 2.28 8.56

2/6/64

;;

~

...rlt:I

?"

!" :I:

"'

td

:>0

t:O ;.-

?"

;:0

J=

rJl

;.-

><:

;.-

td

0

~ :;:::

,51

~

Z

::0 ;.-

':-<

"'Q') "'-

PULMONARY GRANULOMATOSES DUE TO INHALED ORGANIC ANTIGENS

465

Conventional spirometric tests did not reveal any convincing evidence of airway obstruction, but pulmonary compliance was reduced to about 7 per cent of normal. Although not studied in this patient, there can usually also be found a significant increase in pulmonary tissue viscous resistance which, together with the reduction in lung compliance, probably accounts for the characteristically low inspiratory flow rate and related moderate (and usually transient) decrease in maximum voluntary ventilation and forced expiratory volumes. There is always evidence of abnormality in the distribution of inspired gas as revealed by continuous analysis of an expired alveolar sample for nitrogen after a single inspiration of 100 per cent oxygen, but, as is frequently the case, the index of intrapulmonary mixing obtained from measurement of an expired alveolar sample after 100 per cent oxygen for seven minutes was within a normal range. A reduction in arterial saturation to 84 per cent is greater than can be explained by the defect in diffusion, indicating that there is also uneven distribution of pulmonary blood flow and ventilation-perfusion relationships. These defects can also be revealed by a measurable increase in physiologic dead space and in the ratio of dead space to tidal ventilation. Hyperventilation is present at rest as well as on exercise, and as a result arterial carbon dioxide tension is often below normal. Except at the onset, pH is usually normal (compensated respiratory alkalosis). Hemoglobin and hematocrit are normal. Seven weeks later (April 21, 1960) some improvement had occurred in all previously abnormal tests. Using a modification of the technique of Roughton and Forster, the residual abnormality in diffusion appeared to be largely the result of a reduction in diffusing capacity of the pulmonary membrane rather than gross disturbance of the pulmonary capillary circulation. Although not studied in this patient, cardiac catheterization of other patients (Table 3) has revealed only a slight and transient increase in pulmonary artery pressure and arteriolar resistance at this stage. At six months many of the abnormalities had disappeared. Lung compliance was nearly normal, arterial saturation had increased to 94.5 per cent, but pulmonary diffusing capacity and respiratory flow rates were still abnormal. Further improvement was seen in all tests performed January 27,1961. By February 20,1963, normal values had been restored. Compared with the studies performed nearly two years previously, vital capacity and inspiratory capacity had increased approximately 70 and 123 per cent, respectively. Maximum voluntary ventilation had increased 50 per cent and pulmonary diffusing capacity 94 per cent. The following year (February 6, 1964) essentially similar results were seen. It is obvious, therefore, that most of the abnormalities are reversible. Also, it should be noted that, like most healthy farmers, his normal values are probably supernormal. In our experience the healthy, Middle West farmer is 20 per cent or more above the accepted normal standards in many of the commonly used tests of pulmonary function. Too much emphasis, therefore, must not be placed on any single test

466

J.

Table 3.

RANKIN,

M.

KOBAYASHI,

H. A.

BARBEE,

DICKIE

Pulmonary Hemodynamics in Two Patients with Farmer's Lung

Patient Surface area (m. 2) Date of biopsy Date of study Conditions

R. A.

~

Minute volume (L./min. STPDt) O 2 consumption (mL/min. STPD) Arteriovenous O 2 difference (m1./100 mL) Cardiac output (L./min.) Cardiac index (L./min./m.2) Pulmonary artery pressure (mm. Hg) Mean pulmonary artery pressure (mm. Hg) Right ventricular pressure (mm. Hg) End-diastolic pressure in right ventricle (mm. Hg) Total pulmonary resistance (dyne cm.-'/sec.) Right ventricular work (kg. m./min.)

3 1.58 6/21/55 3/3/55

2

1.70 3/28/55 3/24/55 REST

EXERCISE"

REST

EXERCISE*

8.1 254 3.95 6.4 3.8 30.4/8.5

15.9 664 6.22 10.7 6.3 48.5/20

12.7 16 4.46 7.1 4.5 18.2/4.2

13.8 500 6.84 7.3 4.6

18.7 24/-5.5

28

o 233 1.6

10 20.2/-5.0

19.6

3.2 210 3.8

113 0.96

216 0.94

*Exercise for 6 minutes using the bicycle pump technique. tSTPD = standard temperature and pressure, dry.

unless normal values are available for the individual or for other individuals within a similar environmental or occupational or racial group. Rather, by correlation of all tests the pathophysiologic pattern as a whole should be considered. When all the physiologic evidence is considered, a very distinct and uniform pathophysiologic pattern emerges. Briefly, we can deduce that the lung tissue is: (1) stiff and resistant to deformation, which can be attested to by the surgeon and anesthesiologist at the time of lung biopsy; (2) moderately hyperinflated; and (3) has a thickened alveolar capillary membrane. In addition, there is (4) moderate to severe disturbance in the relationship between regional ventilation and circulation; (5) only slight abnormality in the overall pulmonary circulation; and (6) no convincing evidence of abnormality in the conducting airways. As will be seen, these physiologic abnormalities correlate well with the findings obtained on lung biopsy. The value of longitudinal (i.e., repeated) tests of pulmonary function and the inadequacy of any single test is obvious. Late Features Although recovery from any single episode appears to be the rule, protracted exposure or repeated acute episodes may lead to irreversible pulmonary insufficiency. The usual chronic course is typified by a 38year-old farmer (F. K.) who suffered from recurrent acute episodes separated by periods of ill health each winter for about eight years. The roentgenographic (Fig. 3), histopathologic, and physiologic features (Table 4) at this stage are comparable to those found in any form of chronic diffuse interstitial pulmonary fibrosis and are characteristic of

PULMONARY GRANULOMATOSES DUE TO INHALED ORGANIC ANTIGENS

467

what is commonly referred to as the alveolar capillary block syndrome. The fibrotic reaction appeared to be most marked in the centrllobular area. Compared with those patients who showed a granulomatous reaction, there is a greater reduction in static lung volumes and diffusing capacity but relatively less abnormality in maximum voluntary ventilation, ventilation-perfusion anomalies and arterial saturation. He died within three years of progressive pulmonary hypertension and right heart failure . A less common chronic variant is represented by patient H .E. (Table 4), a 60-year-old farmer who, likewise, had suffered from nu~ merous episodes. Roentgenograms (Fig. 4) suggested the presence of emphysema, but pulmonary function tests were less convincing. Unlike the average patient with uncomplicated emphysema, the maximum expiratory flow rates, forces expiratory volumes, and maximum ventilation are relatively well preserved, while pulmonary diffusing capacity and arterial saturation are grossly abnormal. Also, unlike the usual situation in emphysema, inspiratory and expiratory flow rates are similar. Seapo has found occasionally an unusual form of pan acinar emphy-

Figure 3.

Figure 4.

Figure 3. Chest roentgenogram of 42-year-old farmer who had suffered recurrent episodes of chills, fever, dyspnea and cough whenever he handled moldy silage and moldy millet hay. The first episode occurred abruptly in 1947. Minor episodes recurred almost weekly until 1950 when a chest roentgenogram showed a generalized interstitial pneumonitis. He was advised at this time to avoid contact with moldy farm dusts. The acute interstitial pneumonitis resolved in 3 months, leaving some fibrous residuals. By 1955 he was unable to work full time. The current roentgenogram which has remained unchanged since 1955 shows extensive fibrotic disease throughout the right lung, with interspersed emphysema; a considerable amount of change is seen in the upper 213 of the left lung. Some fine granular densities are also present. Figure 4. Chest roentgenogram of 60-year-old farmer whose first episode of interstitial pneumonitis occurred in 1949 following exposure to moldy farm dusts . He had just purchased a farm and was cleaning out dust, dirt and cobwebs which had accumulated since the barn was built in 1912. Since then he has suffered recurrent episodes.

468

J. Table 4.

RANKIN,

M.

KOBAYASHI,

R. A.

BARBEE,

H. A.

DICKIE

Late Physiologic Features in Two Patients PATIENT F. K. Normal Patient

LUNG VOLUMES Vital capacity (L.) Inspiratory capacity (L.) Residual volume (L.) Total lung capacity (L.) MECHANICS OF BREATHING Forced expiratory volume in 1 sec. (L.) Forced vital capacity (L.) Max. expiratory flow rate (L./min.) Max. inspiratory flow rate (L./min.) Max. voluntary ventilation (L./min.) DISTRIBUTION OF INSPIRED GAS N, after 7 min. 0, (%) N, after 7 min. 0, (%) Single breath 0, DIFFUSION AND GAS EXCHANGE Arterial 0, saturation (%) Arterial CO, tension (mm. Hg) Arterial hemoglobin (gm./100 ml.) Arterial pH Diffusing capacity of lung (ml./min./mm. Hg)

PATIENT H. E. Normal Patient

3.95 3.16 1.20 5.15

2.10 1.06 2.39 4.23

3.62 2.89 1.61 5.23

4.91 3.00 4.32 9.22

3.40 4.24 550 450 105

1.86 1.86 333 310 87.9

2.80 3.82 550 450 96

2.26 4.53 300 267 67

< 2.5

0.5

< 2.0

96-99 38-44 13.5-15.5 7.38-7.42 24.1

+

92.6 36.2 13.0 7.47 10.3

96-99 38-44 13.5-15.5 7.38-7.42 26.0

2.5

++++ 84.8 36.4 12.5 7.43 10.0

sema associated with a very fine diffuse interstitial fibrosis. There is no reason, however, why the disease, farmer's lung, should not be superimposed on a case of pulmonary emphysema. This patient may well represent such a combination.

PATHOLOGIC FEATURES Photomicrographs of characteristic areas of specimens obtained by lung biopsy are presented in Figures 2, 5, and 6. An acute granulomatous interstitial pneumonitis has been observed in all but the most chronic cases. 5 , 27 The abnormalities were similar in all sections, and no significant variation was demonstrated which would warrant specific comment. The histologic pattern was characterized by a granulomatous reaction with round cell infiltration, epithelioid cells, and poorly defined tubercles. Occasional scattered giant cells were present in some of the sections; in others these cells were fairly numerous. The alveolar septa were regularly involved throughout the tissue sections. Numerous lymphocytes and plasma cells were present in swollen septa. Polymorphonuclear cells were not evident, and caseous necrosis was not a feature in any of the sections studied. Reticulin and collagen fibers were increased in number, and in some instances the latter formed tonguelike projections into dilated alveolar spaces. Special stains and cultures of the tissues revealed neither mycobacteria or fungi. It should be stressed that this is the evidence available in the subsiding

PULMONARY GRANULOMATOSES DUE TO INHALED ORGANIC ANTIGENS

469

phase of what previously had been a much more acute interstitial lesion, demonstrated by chest roentgenogram in the majority of patients for whom lung biopsies had been taken. Even at this time the alveolar septa universally were involved and thickened. The rapid onset and the rapid clearing, illustrated by the chest roentgenogram, suggest that the interstitial structures were involved in a much more acute reaction with edema and that the granulomatous reaction developed as this condition subsided. The possibility that this type of acute inflammatory reaction is subsequently followed by a granulomatous change is suggested by our experience with erythema nodosa lesions, associated with hilar lymphadenopathy, which have been regarded as manifestations of sarcoidosis. In acute erythema nodosum, biopsy reveals changes which show no granulomatous features. However, if the lesion is allowed to subside and a biopsy is taken from the small residual nodule, it frequently shows a tissue reaction quite characteristic of a sarcoid nodule.

Figure 5. Photomicrograph of lung section of a 17-year-old farmer who developed chills, fever and dyspnea while engaged in stripping moldy tobacco. Cough and dyspnea became progressively worse during the next 2 months and ·then gradually improved. Chest roentgenograms and physiologic studies were characteristic of those described in the text. Histologic sections of lung biopsy specimen obtained 5 months after onset of symptoms show numerous well-formed tubercles. Structural alterations observed in this section provide explanation for some of the physiologic abnormalities. Abnormal relationship between regional ventilation and circulation is to be expected in view of the universal but regionally variable distribution of the granulomatous process as is seen in this section. In addition, there should be significant alteration in the mechanical properties of the lung. Studies performed 2 weeks before lung biopsy revealed a lung compliance of 0.049 L./cm./H,O (approximately 25% of normal), an airway resistance of 1.37 cm. H,O/L./sec. (within normal range) and a tissue resistance of 0.67 cm. H,O/L./sec. (an increase of 90-570%). Reduced from x 50.

470

J.

RANKIN,

M.

KOBAYASHI,

R. A. BARBEE, H. A. DICKIE

Figure 6. Photomicrograph of lung section of a 48-year-old farmer who developed recurrent chills, fever and dyspnea on numerous occasions following the handling of moldy hay. Physiologic abnormalities similar to those seen in Table 3 were demonstrated and direct determin a tion of the mean pulmonary artery pressure was recorded as 37 cm. water at the time of biopsy. The tissue sections show numerous well-formed epithelioid tubercles with a central core of epithelioid cells and Langhan's giant cells surrounded by lymphocytes and plasma cells. This man of small stature (Ht. 66 in., Wt. 136 lb.) had a measured alveolar ventilation of 4.15 L./min./M2 at rest, a physiologic dead space of 200 ml. and a dead space/ tidal ventilation of 43.4%. Distribution of inspired ga s, arterial blood gases and diffusion were grossly abnormal. Reduced from x 145.

The biopsy of patient F.K. whose x-ray and physiologic tests are seen in Figure 3 and Table 4, differed from the others. No evidence of an acute granulomatous reaction was observed. As was predicted from the physiologic tests, the findings are indistinguishable from numerous other forms of chronic diffuse interstitial fibrosis. The gross features at this late stage are variable. In some there is a fine fibrosis with the cut surface resembling generalized emphysema, while in others there are the typical appearances of a honeycomb lung. Thickening of the pulmonary arteries and right ventricular hypertrophy eventually occurs.

IMMUNOLOGIC FEATURES By 1958 we had concluded that farmer's lung was the result of an acquired hypersensitivity to molds or the products of molds in a wide variety of organic materials. 5 Our reasoning was largely as follows. 1. Acute symptoms invariably arise within four to eight hours of exposure to moldy organic dusts. No known infection has such a short incubation period. 2. Corticosteroids provide immediate and effective control of acute symptoms.

PULMONARY GRANULOMATOSES DUE TO INHALED ORGANIC ANTIGENS

471

3. The infiltrative process in the lung consists largely of lymphocytes, which are known to be the carriers of delayed hypersensitivity and to be involved in numerous immunologic reactions, together with plasma cells which are differentiated elements engaged in producing soluble antibody. Immunologic mechanisms have been invoked in other diseases associated With epithelioid granulomas. Our first efforts in 1959 with the predominant known spores such as penicillium and aspergillum were totally unrewarding. In late 1960, we started experiments designed to detect specific precipitating antibodies in sera of patients with farmer's lung against antigens extracted from whole samples of moldy forage. The results of these studies were highly significant and can be summarized as follows: Extraction of Antigens. Several methods I5 • 16• 26 have been used to extract antigens from samples of moldy hay, grain, bagasse, and other vegetable materials suspected to have caused pulmonary disease. The solvents studied for their ability to extract specific antigens included 0.9 per cent sodium chloride containing 0.5 per cent phenol, 0.1 N acetic acid, pH 7.4 phosphate buffer, 0.1 N sodium hydroxide, 50 per cent phenol, and 0.5 M trichloroacetic acid. Although several of the solvents extracted antigens which gave precipitin reactions with farmer's lung sera, trichloroacetic acid was generally used because it gave strong precipitin reactions and was the most selective solvent. Antigens were, therefore, extracted from 15 samples of moldy forage in the following manner. After extraction with acetone, the residue was extracted with 0.5 M trichloroacetic acid, the filtrate dialyzed against running water, the dialyzate concentrated by freeze drying, dissolved in water, and antigens precipitated with ethanol in varying concentrations from 50 to 90 per cent and dried with acetone. Antigenicity of Extracts. Extracts prepared as described above were tested for their ability to precipitate specific antibodies in the serum by double diffusion in agar gels (Fig. 7) by the method of Ouchterlony l8 and by immunoelectrophoresis in agar (Fig. 8) according to the method of Grabar. lo The serum of affected individuals (unlike controls) appeared to contain one to three antibodies which specifically reacted with one to three antigens present in the extracts from moldy hay. Usually, one or two precipitin lines were obtained with double diffusion and two or three with immunoelectrophoretic techniques (Table 5). Similarly, prepared extracts of fresh hay produced no precipitins with either technique. These trichloroacetic acid (TeA) soluble antigens were heat stable, stable to wide ranges of pH, and reacted with Schiff's reagent for carbohydrate which

Figure 7. Agar diffusion precipitation of antigens with farmer's lung serum. The center well (W) contained farmer's lung serum; each outer well contained 15 mg/ml of an antigen preparation. Well No. 1 contained antigen preparation from moldy hay No. Mh-1; No. 2, UH-1; No. 3, H-1; No. 4, H-65; No. 5, M; and No. 6, MH-44.

472

J.

RANKIN,

M.

KOBAYASHI,

R. A.

BARBEE,

H. A.

DICKIE

Figure 8. Immunoelectrophoreses of sera with farmer's lung antigens. The small wells labeled F-90, F-90., M" V" and V 2 , contain 15 mg/ml of antigen extracted from several different samples of moldy hay from farms in Wisconsin. M-44 contains an antigen extract obtained from Dr. J. Pepys, Institute of Disea ses of the Chest, London. CA contained an extract of good commercial alfalfa. The troughs labeled (n) contained normal serum ; those labeled H were filled with farmer's lung serum. Typical arcs in the A, B and C regions are seen when farmer's lung sera are reacted with antigens labeled F-90, F-90., M" and V 2 • No precipitins are observed with extracts of good hay (CA) or normal serum (n).

Table 5. Variation in Concentration and Number of Specific Antigens'" ANTIGEN

MH-1 VH-1 VH-2

HI-1

DILUTION ENDPOINT

NO. OF PRECIPITATION LINES

Double Diffusion

Double Diffusion

Immunoelectrophoresis

8-128 4-64 0-2 32-128

1-2 1-2

2-3 2-3 2 2-3

0-1 1-2

*Number and dilution endpoint of precipitation lines from antigens in different samples of moldy hay when tested against sera from 4 patients. suggested that the antigens contained much carbohydrate. LaBerge and Stahmann l 6 have shown that they are composed of peptides and carbohydrates which were not separated by TCA extraction, alcohol fractionation, or by chromatography on diethylaminoethyl (DEAE) cellulose ion exchange columns. When tested by immunoelectrophoresis, two of these antigens (A and B) had a negative charge, and one (C) had no charge, thus giving rise to arcs in the A, B and C regions referred to by P epys l9. 21 as Farmer's Lung Hay (F.L.H.) reactions. Using the usual Coca's fluid extract of moldy hay, P epys l9. 21 has obtained essentially similar results in affected farmers . However, unlike the TCA-soluble antigens, the antigens extracted by Coca's fluid give positive results with 18 per cent of unaffected farmers as well as 15 to 20 per cent of farmers with other lung diseases. For a detailed account of the theoretical and practical significance of these differences the reader should consult references 16 and 19.

473

PULMONARY GRANULOMATOSES DUE TO INHALED ORGANIC ANTIGENS

CORRELATION BETWEEN CLINICAL DIAGNOSIS AND IMMUNOCHEMICAL PRECIPITATION. In 1961 we examined sera from 36 patients in whom a definite clinical diagnosis of farmer's lung had been established by extensive clinical, roentgenographic, physiologic and, in some instances, pathologic studies. Seven of these sera were collected from acutely ill patients and the remainder from asymptomatic farmers who had suffered from this disorder during the past 1 to 18 years. These 36 sera and 36 control specimens collected from farmers exposed to the same dusts as well as from patients with sarcoidosis, fungus infections, and other unrelated pulmonary diseases were tested against antigens prepared from moldy hays. The results, which were first reported in 1962,25.31 are shown in Table 6. Since then, they have been confirmed repeatedly. In a random sample of 81 farmers who had suffered from a typical episode of pneumonitis any time during the previous 20 years, positive results were obtained in 64 (79 per cent). On the other hand, no precipitins were found in the serum of 106 controls who included 35 farmers without disease, as well as patients with sarcoidosis, systemic fungus infections, silo-filler's disease and other pulmonary diseases. The incidence of positive serological results, as expected, was highest in those patients studied soon after exposure and was 94 per cent in those studied within a year of an acute episode of interstitial pneumonitis. After two years 90 per cent and after five years 70 per cent of sera still retained significant titers of precipitating antibody. Indeed, even in the absence of any recognizable recurrence of illness, several apparently healthy individuals (including some who had had no farm exposure for many years) still retained measurable quantities of antibody 10 to 20 years later. The antibodies were present in the 7S gamma globulin fraction of the serum. THERMOPHILIC ACTINOMYCETES AS A SOURCE OF FARMER'S LUNG ANTIGEN. In Figure 7 the large center well contains serum from a farmer's lung patient (W). The six outer wells contain the moldy hay antigen preparations. Wells No. 1, 2, and 3 represent those prepared from moldy hay samples obtained from Wisconsin farms. Well No. 4 contains the antigens from a sample sent to us by Dr. P. H. Gregory,

Table 6. Correlation Between Clinical Diagnosis and Immunochemical Precipitation IMMUNOCHEMICAL PRECIPITATION"

NO.

Patients Symptomatic Asymptomatic Total Controlst

7 29 36 38

++

+

7 6 13

11 11

0

0 0

*Against a mixture of antigens from 4 moldy hays.

tFarmers and patients with other pulmonary diseases.

REACTORS

+

%

o

100

o

0

12 12

59 67

474

J.

RANKIN,

M.

KOBAYASHI,

R. A.

BARBEE,

H. A.

DICKIE

Rothamsted Experimental Station, Harpenden, England, that was produced by inoculating cold sterilized, good quality hay with a spore suspension obtained from hay known to cause farmer's lung in England. Well No. 5 contained antigens from moldy hays prepared by Dr. Gregory by inoculation with a mixture of known fungi. Well No. 6 contained an antigen extract obtained from Dr. J. Pepys, Institute of Diseases of the Chest, London, that was prepared from English hay known to cause farmer's lung. Each of the preparations formed one or more precipitin lines. Some of these lines seemed to merge at their junction, suggesting common antigens in the different moldy hay samples. From these and similar studies of some 17 samples of moldy hay we concluded that there was probably only a small number, possibly 1,2, or 3, of antigens associated with farmer's lung,25, 26, 31 and these were related to the fungal or other spores present. Gregory and Laceyll simultaneously demonstrated that hay which caused farmer's lung had evidently become heated spontaneously during maturation, that it contained a higher pH than good hay and that its dust contained more thermophilic molds and actinomycete spores. Only 1 to 2 per cent of the actinomycete spores could be grown in culture. However, one of them, Thermopolyspora polyspora, was the richest source of antigens yet found. Further, Pepys et al. 19,21 provided convincing evidence that extracts of T. polyspora, obtained from cultures on ordinary media, contained antigens similar to those found in moldy hay. In farmer's lung due to moldy hay, 87 per cent of the sera reacted to T. polyspora and about 3 per cent to other actinomycetes, particularly Micromonospora vulgaris. Our own results have been very similar. Gregory examined our H-1 moldy hay sample, the most potent naturally occurring source of antigen we had encountered and which had been used as a standard for all but our most recent studies. 16, 25, 26, 31 T. polyspora and M. vulgaris were the principal organisms identified. Also, the trichloroacetic acid (TCA) soluble antigens from T. polyspora had the same immunoelectrophoretic properties as the three farmer's lung antigens in the moldy hay sample from which this organism was isolated. Additional studies by LaBerge and Stahmann I6 have indicated that the antigens responsible for farmer's lung reactions are glycopeptides and that the peptide may be part of the structural wall of T. polyspora. The antigenic fractions were composed primarily of polysaccharides containing galactose, arabinose and glucosamine. Extracts made from laboratory cultures of T. polyspora, however, gave positive reactions in only 70 per cent of the sera that had been found to react with extracts of moldy hay. Part of the discrepancy is due to the fact that extract of the culture of T. polyspora on nutrient medium has been found to be less potent than when it is grown on hay, and minor antigenic differences have also been found'" A few additional positive reactions may be obtained with M. vulgaris. However, moldy hay appears to contain other as yet unidentified sources of antigen. Moldy hay may contain up to 250,000,000 spores per gram dry weight, many of them actinomycetes 98 per cent of which have not yet been grown in culture. A farmer working in a barn with a moderately dusty moldy hay retains in his lungs as many as 750,000 spores/min.; and, since the T. polyspora spores are 1 JJ- in diameter, they can penetrate into the deepest parts of the lung where, indeed, the tissue reaction occurs.I7

PULMONARY GRANULOMATOSES DUE TO INHALED ORGANIC ANTIGENS

475

PATHOGENICITY OF ANTIGEN EXTRACTS. Moldy forage contains a wide range of substances which are potently anti genic for man;20 therefore, it is difficult to be certain whether the finding of precipitins in sera of patients with farmer's lung or related disorders is evidence only of exposure to moldy farm dusts or whether a true causal relationship exists between exposure to these glycopeptide antigens and the subsequent development of pulmonary disease. Therefore, 100 mg. of antigen extracted from HI was lyophilized, diluted in sterile saline, Seitz filtered, and administered by aerosol (De Vilbiss Nu. 40 Nebulizer) to susceptible farmers and healthy urban controls. I Only a small portion of the antigen was retained. Briefly, the results were as follows: Patients. In susceptible farmers a febrile illness with clinical and physiologic features qualitatively similar to their naturally occurring illness resulted within four to six hours. The reaction varied with their immunologic status as judged by crude estimates of the level of circulating antibody. Chills, fever (as high as 1040 F.), cough, dyspnea, polymorphonuclear leukocytosis, and lymphopenia, together with a sharp drop in diffusing capacity or arterial saturation were seen in every individual with a detectable level of circulating antibody. The average temperature increase throughout a 14-hour period of observation was 2.70 F. Diffusing capacity decreased as much as 50 per cent. Within 24 hours all abnormalities had disappeared. A typical example is seen in Figure 9. Controls. None of the control subjects experienced any respiratory symptoms, nor did they develop lymphopenia or any detectable change in pulmonary function. However, the antigen extracts were not completely innocuous since several experienced slight malaise and fever (average increase, 0.90 F.) associated with a significant polymorphonuclear leukocytosis. Similar results were obtained by Williams who used an extract of moldy h ay 36 and, more recently, by Pepys who used a culture filtrate of T. polyspora grown on nutrient agar. 19 Moreover, it has been shown that both the A and B fraction and the C fraction of T. polyspora are capable of provoking reactions. 19 Farmer's lung is probably as old as settled agrarian civilization. It seems probable that the "Diseases of Sifters and Measurers of Grain" described by Ramazzini in 1713,24 included the condition now known as farmer's lung. Ramazzini attributed the appearance of respiratory disease to the inhalation of dust from damp, moldy overheated grains which had not been properly dried before storage. However, it was first described as a clinical entity by Campbell in 1932 4 and Fawcitt in 1936. 7 Since then, the disease has been reported in Sweden, Norway, Belgium, Denmark, France, Switzerland, Eire, Iceland, Canada, and the United States. In several of these countries it has recently been recognized as a serious occupational hazard. In England and Wales an annual incidence of 10.5 to 193.1 per 100,000 has been reported. 32 The incidence has been found to vary with the summer rainfall totals. When crops are harvested in rainy weather and stored in closed barns and silos, the forking out of moldy bales of hay, the threshing

476

1.

RANKIN,

M.

KOBAYASHI,

R. A. BARBEE, H. A. DICKIE

TEMP. F

DL% of

U

PRECHALLENGE 98%

+5 -

,....,

+4 -

F C

+3 -

, ,, I

I

98%

100

89'\'. 80

C

FC

60

~ I

+2 _

40

+1-

20

4

10

12

14

24

TIME IN HOURS

Figure 9. Temperature response and carbon monoxide diffusing capacity following inhalation of farmer's lung antigens. The temperature response (Fahrenheit) of one of the farmers (F) vs. a control subject (C) is shown by the dotted line and the solid line respectively. Diffusing capacity (DL) for carbon monoxide as a percentage of the prechallenge value is shown on the open bars CC) and striped bars (F).

of poor quality grain, or the sweeping out of closed barns may produce clouds of dust containing fine vegetable matter laden with mold spores. All observers now agree that farmer's lung results from inhalation of such dusts. The original hypothesis that farmer's lung is a form of bronchopulmonary mycosis 7 • 34 can no longer be held tenable. Neither is it likely that nonspecific irritants 8 ,33 or plugging of terminal portions of the bronchial system by mold spores 37 are of etiologic significance.

Conclusions The apparent serologic specificity of antigens extracted from moldy hay, together with their ability to reproduce some of the clinical and physiologic features of the disease after an inhalational challenge of relatively pure antigens, suggests that these antigens are, indeed, responsible for the disease. Available evidence appears to indicate that this unique granulomatous interstitial pneumonitis is the result of an acquired hypersensitivity to relatively simple polysaccharide or glycopeptide antigens formed by the growth of thermophilic actinomycetes and perhaps other, as yet unidentified, organisms on a variety of plant

PULMONARY GRANULOMATOSES DUE TO INHALED ORGANIC ANTIGENS

477

materials. The relatively large quantity of antibody present is compatible with the held view that sarcoid-like granulomas are a response to the formation of antigen-antibody aggregates in the lung of hypersensitive individuals. 9 Furthermore, evidence is accumulating that several other forms of diffuse lung disease arise through similar mechanisms and that farmer's lung is merely one clinical expression of a fundamental immunopathologic process. Farmer's lung hay precipitins have also been obtained in 71 per cent of cattle suffering from fog fever, a disease probably identical with farmer's lung. 14

RELATED DISEASES Bird Breeder's (Fancier's) Lung An important and not uncommon source of inhaled antigens capable of producing an identical clinical, radiologic, physiologic, immunologic and pathologic syndrome is avian excreta from pigeons and budgerigars. 12 • 28 The serum of affected individuals contains high titers of precipitating antibody against pigeon or budgerigar serum proteins, egg proteins, feathers, and other antigens in their excreta. Provocative inhalational challenges with these antigens produced a febrile reaction, associated with crepitant rales and physiologic evidence of an acute interstitial pulmonary reaction qualitatively similar to the naturally occurring disease. Saline extracts of bagasse and mushroom compost and an extract of moldy hay prepared by the method of Kobayashi and associates 15 each produced faint precipitin lines with the serum of at least two of the three patients studied by Reed and associates. These antigens showed reactions of nonidentity with the pigeon antigens, and adsorption of the sera with moldy hay extract did not alter the subsequent reaction with pigeon antigen. On the other hand, sera of patients with farmer's lung do not react with pigeon antigens. Extracts of feathers or droppings of chicken, turkey, quail, duck, and goose showed no precipitin reaction. Immunoelectrophoresis of pigeon serum revealed the major antigen was ')I-globulin, but a- and ,B-globulins and albumin were also precipitated. Cross adsorption studies indicated that the antigens in the serum and droppings were not identical. Almost all the patients described by Hargreave et alY gave striking Arthus-type reactions to intracutaneous tests with undiluted pigeon and budgerigar serum in contrast to the negative reactions observed with weaker extracts. 2H There were a number of unaffected pigeon breeders who had precipitins in their serum. Positive reactions were also obtained in the sera of some cases which had been diagnosed as sarcoidosis or diffuse fibrosis and which had been exposed to birds. 12

Maple Bark Disease In 1932 T owey 35 and his associates reported on 35lumbermen with a respiratory illness similar to farmer's lung (Coniosporiosis), believed due to the spores tentatively identified as Conosporium corticale, found

478

J.

RANKIN,

M.

KOBAYASHI,

R. A.

BARBEE,

H. A.

DICKIE

in infected maple bark. More recently, Emanuel and his co-workers 6 have isolated these spores (now identified as Cryptostroma corticale) from a lung biopsy of a patient with a granulomatous interstitial pneumonitis and have found specific precipitating antibodies in the sera of affected individuals. Bagassosis The condition known as bagassosis, first recognized in Louisiana in 1937, presents a clinical syndrome identical in every respect with that of farmer's lung. The acute respiratory illness primarily affects workers who handle bales of "bagasse" or dried sugar cane fiber. Bagasse is ubiquitous in distribution and has many uses, such as the manufacture of paper, cardboard, gardening mulch, and a variety of building materials. 3 . 29 The disease has been reported from Louisiana, Texas, Missouri, Illinois, Puerto Rico, India, Italy, England, and Peru, and nearly 400 cases have been mentioned in the world literature. Approximately 50 per cent of exposed individuals develop the disease. Precipitating antibodies against extracts of moldy bagasse have been found in the sera of affected individuals,29 but only very occasionally in individuals who have had no contact with bagasse. One extract of fungusladen material elicited a reaction in 71 per cent of the workers tested. Extracts of fresh .bagasse showed a marked decrease in antigenicity but were still capable of eliciting precipitins in the sera of 15 to 29 per cent of patients. It was postulated 29 that antigenic substances are formed in bagasse by the action of fungi under appropriate conditions and that these substances may play an important role in the pathogenesis of bagassosis. Some samples contain as many as 500,000,000 fungal spores per gram. It seems likely that, as in farmer's lung, thermophilic actinomycetes may play an important etiological role. Mushroom Worker's Disease A disease similar to farmer's lung has been described in Puerto Rican migratory workers handling compost used for growing mushrooms 2 in Pennsylvania. In the mushroom industry when compost is being prepared for seeding, it is pasteurized by live steam to an average temperature of 150° F. for five days. Then the damp compost of horse manure and straw is laid down in tiers and maintained at 70 to 80° F. The beds become dry and after harvesting the surface is covered by a thick white mold. It is not unlikely that thermophilic actinomycetes similar to those found in moldy hay are responsible for this illness. Iatrogenic Lung Disease Pulmonary and systemic reactions like those of farmer's lung occur also in response to inhaled dusts of animal origin. For example, patients with diabetes insipidus and under treatment by inhalation of porcine and bovine pituitary snuff may develop asthmatic symptoms due to the heterologous antigens, and also reactions with or without asthma, in the interstitial tissues of the lung like those of farmer's lung. 22 Precipitins are present in these subjects against the porcine

PULMONARY GRANULOMATOSES DUE TO INHALED ORGANIC ANTIGENS

479

and bovine serum proteins and against the pituitary antigens. The precipitins against pituitary antigens also react with antigens in the human anterior and posterior pituitary gland. Thus, iatrogenic autoreactive antibodies also resulted from the inhalation of the heterologous organ antigens - a finding of considerable interest. 22

Miscellaneous Textile workers exposed to size derived from tamarind seed, laboratory technicians exposed to tuberculoproteins, and cave explorers exposed to bat guano have probably suffered from a similar clinical syndrome.

DIAGNOSIS Clinical Features Farmer's lung, bird breeder's (fancier's) lung, bagassosis, and related syndromes listed above constitute a readily recognized and distinct clinical entity. A history of exposure to one of the offending dusts listed in Table 1 followed within a few hours by shaking chills, high fever, and dyspnea is unique to this disease. There is, however, considerable variation in the clinical picture depending on the level of individual sensitivity and the extent of exposure. At one end of the spectrum is the patient with a high fever and alarming acute respiratory insufficiency and at the other, the patient with the insidious onset of a nonproductive cough and slowly progressive shortness of breath. The generalized finely granular reticular pattern of the chest roentgenogram is almost pathognomonic. The rapid clearing of the interstitial pattern is rarely seen in other diseases which produce a similar radiologic picture. Conversely, the absence of recognized roentgen evidence of an interstitial pneumonitis does not exclude a diagnosis of any of the diseases under discussion. The very fine diffuse reticular pattern is often difficult to recognize by standard roentgenographic techniques. Also, at the chronic stage, the type of fibrosis produced is not radiologically distinguishable from that due to several other pathological conditions.

Pulmonary Function Tests Tests of pulmonary function clearly demonstrate involvement of the interstitial tissues of the lung and the absence of significant disease in the airways. Moreover, qualitatively, there are recognizable differences between this and other, more chronic forms of diffuse interstitial disease.;; The probability of almost complete functional recovery exists in few other diseases with which it may be confused. When physiologic tests are repeated over a period of time, the characteristic physiologic syndrome is easily recognized. Abnormalities are most marked immediately after exposure. Provided further contact is a voided, ,:there is a striking improvement in most tests of pulmonary function !followed by gradual improvement in diffusing capacity to normal values ~ 3 to 12 months.

480

J.

RANKIN,

M.

KOBAYASHI,

R. A.

BARBEE,

H. A.

DICKIE

Lung Biopsy This procedure will rarely be called for but, on occasion, can be helpful, particularly in cases with an insidious onset. The histopathology is recognizably different from that seen in other granulomatous reactions. In sarcoidosis the tubercles are larger and more discrete with relatively normal framework seen in the intervening tissue. The miliary lesions of tuberculous and fungous infections (especially histoplasmosis, blastomycosis, and coccidioidomycosis) are, likewise, more discrete, and well-formed tubercles are present. In the larger and older tubercles some caseation necrosis is almost always present, and a few areas of calcification may be evident. Alveolar septa well beyond the tubercle show little, if any, thickening. Mycobacteria and fungi can usually be demonstrated by special stains and cultures. The granulomatous reaction seen in beryllium disease of the lung is probably the most difficult lesion to differentiate by histologic study. However, in this condition, some necrotic centers of the granulomas contain well-preserved as well as degenerating neutrophils. In longstanding beryllium disease, the interstitial structures are more fibrotic and less acutely involved. Without a history of exposure to beryllium and spectrographic evidence of beryllium in the tissues, the diagnosis could be confused on histologic evidence alone. The more fibrotic reaction seen in patients with chronic disease cannot be differentiated from other forms of interstitial fibrosis. Although histologic study alone may occasionally (though rarely) fail to provide an etiologic diagnosis, correlation of the pathologic findings with the natural history of the disease (as revealed by clinical and physiologic evidence) will, in our experience, differentiate the disorders under discussion from other forms of pulmonary granulomatosis and fibrosis.

Serologic Tests The finding of precipitins in the serum against antigens present in organic dusts provides valuable evidence of exposure to particular antigens. Moreover, high titers are rarely found in individuals who have not suffered from one of the clinical syndromes described here. Although not always diagnostic, they can help in confirming a clinical diagnosis in 90 per cent or more of cases of farmer's lung and afford a reliable method of distinguishing this disease from other forms of diffuse pulmonary disease. Moreover, they can be expected to help in distinguishing 80 per cent or so of cases in which some other respiratory condition such as chronic bronchitis or emphysema is involved. While a negative result does not support a diagnosis, it does not exclude it. It may merely mean that the appropriate antigen has not been found. The double diffusion test tends to be more sensitive than the immunoelectrophoresis test, but the latter is more discriminating. It must, however, be emphasized that the interpretation of the precipitin reactions requires care since fungi, vegetable dusts, and even nematode parasites contain C-substance-like materials which precipitate C-reactive protein if it is present in the serum. Attention has recently been

PULMONARY GRANULOMATOSES DUE TO INHALED ORGANIC ANTIGENS

481

drawn to this problem by Salvaggio and his colleagues in their study of bagassosis. 29 Provocative Inhalation Tests A provocative inhalational challenge with a suspected antigen may be of considerable diagnostic value, since it produces transient clinical and physiologic findings qualitatively similar to the naturally occurring disease. However, the procedure is time-consuming, requires complicated equipment, and is potentially dangerous or at least uncomfortable to the patient and must be undertaken in a hospital. Moreover, interpretation of the results requires caution. Extracts of moldy hay, pigeon excreta, and pigeon sera may contain materials capable of provoking a febrile reaction in normal subjects, although these reactions are less marked than in affected subjects and are not accompanied by pulmonary changes.

SUMMARY Inhalation of a wide variety of organic dusts by individuals sensitive to antigens present in the dusts may result in acute, chronic, or recurrent lung disease with symptoms and signs attributable to a reaction in the most peripheral part of the bronchopulmonary tree. High titers of precipitating antibody against antigens present in the dusts are found in the sera of affected individuals. The most striking tissue reactions consist of diffuse infiltration of the interstitial tissues of the lung with plasma cells and lymphocytes, epithelioid cells, poorly defined tubercles, and Langhan's giant cells. The various disease known as farmer's lung, thresher's lung, bagassosis, mushroom worker's disease, maple bark disease, bird breeder's (fancier's) lung and probably several other conditions are merely different clinical expressions of the same basic immunopathologic mechanism. The antigens capable of producing this type of reaction are ubiquitous, and are likely to be a fairly common cause of lung disease. In most instances, diagnosis can be established by the judicious combination of clinical, radiologic, physiologic, serologic, and histologic techniques.

REFERENCES 1. Barbee, R. A., Rankin" J., and Dickie, H. A.: The pathogenicity of specific glycopeptide antigens in farmer's lung. Proc. Soc. Exper. BioI. & Med. 118:546, 1965. 2. Bringhurst, L. 5., Byrne, R. N., and Gershon-Cohen, J.: Respiratory diseases of mushroom workers: Farmer's lung. J.A.M.A. 171 :15,1959. 3. Buechner, H., et al.: Bagassosis: Review with further historical data, studies of pulmonary function, and results of adrenal steroid therapy. Am. J. Med. 25:234,1958. 4. Campbell, J. M.: Acute symptoms following work with hay. Brit. M. J. 2:1143, 1932. 5. Dickie, H. A., and Rankin, J.: Farmer's lung: an acute granulomatous interstitial pneumonitis occurring in agricultural workers. J.A.M.A. 167:1069, 1958. Interstitial diseases of the lungs: The alveolar capillary block syndrome. In Clinical Cardiopulmonary Physiology. CB. L. Gordon, Ed.). New York, Grune & Stratton, 1960, Chap. 51, p.8lO.

6. Emanuel, D., Lawton, B., and Wenzel, F.: Maple bark disease. New England J. Med. 266:333,1962. 7. Fawcitt, R.: Fungoid conditions of lung: I. Brit. J. Radiol. 9: 172 (March) 1936. Fungoid conditions of lung: n. Ibid. 9:354 (June) 1936. Occupational diseases of lungs in agricultural workers. Ibid. 11 :378 (June) 1938.

482

J.

RANKIN,

M.

KOBAYASHI,

R. A.

BARBEE,

H. A.

DrCKIE

8. Fuller, C. J.: Farmer's lung: A review of present knowledge. Thorax 8:59,1953. 9. Germuth, F. G., Jr., and Pollack, A. D.: Production of lesions of serum sickness in normal animals by the passive transfer of antibody in the presence of antigen. Bull. J ohns Hopkins Hosp. 102:245, 1958. 10. Grabar, P., and Williams, C. A.: Methode permettant l'etude conjuguee des proprietes electrophoretiques et immunochimiques d'un melange de proteines: application au serum sanguin. Biochem. Biophys. Acta 10:193,1953. 11. Gregory, P. H., and Lacey, M. E.: Mycological examination of dust from mouldy hay associated with farmer's lung disease. J. Gen. Microbiol. 30:75,1963. 12. Hargreave, F. E., Pepys, J., Longbottom, J. L., and Wraith, D. G.: Bird breeder's (fancier's) lung. Lancet 1 :444, 1966. 13. Jenkins, P. A.: Immunological studies in farmer's lung. Ph.D. thesis presented to University of London, 1964. 14. Jenkins, P. A., and Pepys, J.: Fog fever: Precipitin (F.L.H.) reactions to mouldy hay. Vet. Rec. 77:464, 1965. 15. Kobayashi, M., Stahmann, M. A., Rankin, J., and Dickie, H. A.: Antigens in mouldy hay as the cause of farmer's lung. Proc. Soc. Experi. BioI. & Med. 113:472, 1963. 16. LaBerge, D. E., and Stahmann, M. A.: Antigens from mouldy hay involved in farmer's lung. Proc. Soc. Exper. BioI. & Med. 119:463, 1966. 17. Lacey, J., and Lacey, M. E.: Spore concentrations in the air of farm buildings. Tr. Brit. Mycol. Soc. 47:547, 1964. 18. Ouchterlony, 0.: Antigen-antibody reactions in gels. Acta Path. Microbiol. Scand. 32:231, 1953. 19. Pepys, J., and Jenkins, P. A.: Precipitin (F.L.H.) test in farmer's lung. Thorax 20:21,1965. 20. Pepys, J., Longbottom, J. L., and Jenkins, P. A.: Vegetable dust pneumoconioses: Immunologic responses to vegetable dusts and their flora. Am. Rev. Resp. Dis. 89:842,1964. 21. Pepys, J., Jenkins, P. A., Festenstein, G. N., Gregory, P. H., Lacey, M. E., and Skinner, F. A.: Farmer's lung: thermophilic actinomycetes as a source of "farmer's lung hay" antigens. Lancet 2:607,1963. 22. Pepys,]., Jenkins, P. A., Lachmann, P. J., and Mahon, W. E.: An iatrogenic auto-antibody: Immunological responses to pituitary snuff in patients with diabetes insipidus. Clin. & Exper. lmmunol. 1: (In press), 1966. 23. Pepys, J., Riddell, R. W., Citron, K. M., and Clayton, Y. M.: Precipitins against extracts of hay and moulds in the serum of patients with farmer's lung, aspergillosis, asthma and sarcoidosis. Thorax 17:366,1962. 24. Ramazzini, B.: De morbus artificum diatriaba, 1713. Published by the University of Chicago Press, Chicago, 1940. 25. Rankin, J., Dickie, H. A., Kobayashi, M., and Stahmann, M. A.: Pathogenesis of farmer's lung. J. Lab. & Clin. Med. 60:1008,1962. 26. Rankin, J., Kobayashi, M., Barbee, R. A., and Dickie, H. A.: Agricultural dusts and diffuse pulmonary fibrosis. Arch. Envir. Health 10:272,1965. 27. Rankin, J., Jaeschke, W. H., Callies, Q. C., and Dickie, H. A.: Farmer's lung: physiopathologic features of the acute interstitial granulomatous pneumonitis of agricultural workers. Ann. lnt. Med. 57:606, 1962. 28. Reed, C. E., Sosman, A., and Barbee, R. A.: Pigeon breeder's lung: A newly observed interstitial pulmonary disease. J .A.M.A. 193 :261, 1965. 29. Salvaggio, J. E., Buechner, H. A., Seabury, J. H., and Arguembourg, P.: Bagassosis: I. Precipitins against extracts of crude bagasse in the serum of patients. Ann. lnt. Med. 64:748, 1966. 30. Seal, R. M. E., Thomas, G. 0., and Griffiths, J. J.: Farmer's lung. Proc. Royal Soc. Med. 56:271,1963. 31. Stahmann, M. A., and Kobayashi, M.: Farmer's lung: Immuno-chemistry. Consultant's Conference Abstracts of Contributors. Institute of Diseases of the Chest, London, England, p. 21,1962. 32. Staines, F. H., and Forman, J. A. S.: A survey of farmer's lung. J. CoIl. Gen. Practit. 4:351,1961. 33. Studdert, T. C.: Farmer's lung. Brit. M. J. 1: 1305, 1953. 34. Tomell, E.: Thresher's lung: fungoid disease resembling tuberculosis or morbus Schaumann. Acta med. scandinav. 125: 191,1946. 35. Towey, J. W., Sweany, H. C., and Huron, W. H.: Severe bronchial asthma apparently due to fungus spores in maple bark. J.A.M.A. 99:453, 1932. 36. Williams, J. V.: Inhalation and skin tests with extracts of hay and fungi in patients with farmer's lung. Thorax 18:182, 1963. Pulmonary function studies in patients with farmer's lung. Thorax 18:255, 1963. 37. Williams, D. I., and Mulhall, P. P.: Farmer's lung in Radnor and North Breconshire. Brit. M. J. 2: 1216,1956. 1300 University Avenue Madison, Wisconsin 53706