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The pattern of eosinophilia in premature infants
612
April 1981 The Journal of P E D I A T R I C S
The pattern of eosinophilia in premature infants A prospective study in premature infants using the absolute eosinophil count
The incidence and severity of eosinophilia was prospectively studied in 45 premature infants, who were divided into three groups according to their gestational age, The incidence and severity of eosinophilia was higher in smaller preterm infants. A significantly higher number of infants with eosinophilia received total parenteral nutrition, endotracheal intubation, or blood transfusions. The duration of total parenteral nutrition or endotracheal intubation and the number of blood transfusions were also significantly higher in infants with eosinophilia. Eosinophilia in premature infants is not associated with neutropenia.
Abdul M. Bhat, M.B.B.S.,* and John W. Scanion, M.D., Washington, D.C.
EOSINOPHILIA occurs frequently in premature infants ~-'~ but the mechanism has not been elucidated. Eosinophilia has been associated with total parenteral nutrition s and with cow milk allergy in premature infants? In a retrospective study, Gibson et aP found eosinophilia to be associated with an anabolic state in preterm infants; infants had eosinophilia only after steady weight gain was established, and there was no relationship between gestational age and degree of eosinophilia. We undertook a prospective study of the incidence of eosinophitia in premature infants to detect differences in the incidence, severity, and duration of eosinophilia among infants of various gestational ages and birth weights. This study also investigated the relationship between total parenteral nutrition or oral nutrition (human milk or formula) and eosinophilia. Other clinical phenomena were also analyzed for their relationship with the onset, incidence, and severity of eosinophilia.
MATERIAL AND M E T H O D S From September, 1979, to March, 1980, 45 preterm infants below 37 weeks' gestationaI age were admitted to
From the Division of Neonatology, Columbia Hospital for Women, and Department of Pediatrics (Neonatology), Georgetown University Hospital Supported by a grant from the Research Foundation of The Columbia Hospital for Women. *Reprint address: Division of Neonatology, Hurley Medical Center, Number One Hurley Plaza, Flint, MI 48502. VoL 98, No. 4, pp. 612-616
our nurseries and eligible for the study. The gestational age of all subjects was estimated by the method of Dubowitz et al. 7 Infants with congenital abnormalities, those small for gestational age, twins, and those receiving corticosteroids were excluded, Abbreviations used AEC: absolute eosinophil count TPN: total parenteral nutrition ET: endotracheal For analysis, 45 appropriate for gestational age infants were divided into three groups based on gestational age. Group I was comprised of 16 infants at 30 weeks or below (27.4 • 1.45 mean -_+ SD); their weights varied from 780 to 1,200 gm (942 • 139). Group II was comprised of 13 infants between 31 and 33 weeks (31.7-4-0.69); their weights varied from 1,300 to 1,540 gm (1,391-+-89). Group I l i was comprised of 16 infants between 34 and 36 weeks (34.2 • 0.54); their weights varied f r o m 1,540 to 1,880 gm (1,704 _+ 87). Absolute eosinophil count was done with the UNOPETTE, test 5877 system (Beckton Dickinson and Company, Rutherford, N. J.). This procedure uses a modified Pilot solution containing phloxine B as the selective stain for eosinophils? Propylene, glycol, incorporated in the diluent, acts as the vehicle for the phloxine B stain and renders erythrocytes relatively nonrefractile so they do not interfere with the visual counting procedure. 9 AEC determined this way compares favorably with that determined 0022-3476/81/040612+05500.50/0 9 1981 The C. V. Mosby Co.
Pattern of eosinophiiia in premature infants
Volume 98 Number 4
6 13
EOSINOPHILIA IN GROUP I PREMATURE INFANTS (Mgan ~ $ 0 and Range) Birthweight regained - Mean
8O00 7000
I Range
500, E
"-- 4 0 0 , "E o
~
&!iiill
300(
=o
/
~, 2 0 0 0 "S
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-2o 'Age of p r e m a l u r e
5'0
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I
8'o
L
9o
,oo
(days)
Fig. 1. Mean, standard deviation (shaded area), and range Of serial AEC in Group I infants. Number of infants = 16. Age when eosinophilia started-13.3 +_ 5.3days (mean • SD); age when eos!nophilia peaked-27.4 • 5.6 days; duration of eosinophilia--44.6 • 26.8 days; agewhen birth weight regained-2L2 • 7.4 days.
by the Thoma-White cell pipette using a modified Pilot solution? ~ " This procedure is more accurate and precise than an eosinophil count estimated from a peripheral blood smear. All eosinophil counts were performed by one of the authors (A. M. B.) to ensure similar methods and consistency in counting. Eosinophilia was defined ~ as an absolute eosinophil count more than 700/mint Mild eosinophilia was defined as an AEC between 700 and 999/mm:~; 1,000 to 2,999/ mm 3 was classified as moderate; more than 3,000/mm" was considered9to be severe eosinophilia. All infants had an AEC performed within 24 hours after birth, then twice weekly until discharge. Their weight, length, head circumference, number of blood transfusions, duration of endotracheal intubation, and nutritional intake (type and volume) were carefully recorded. Any significant clinical events occurring during the nursery stay were noted. Statistical analysis on parametric data was done using the Student t test or correlation analysis. Nonparametric data were analyzed by X= with Yates correction or the Fisher exact test. The clinical study was approved by the Human Research Committee of Georgetown University Hospital. Written informed consent was obtained from all parents. RESULTS Thirty-four (75.5%) of 45 infants studied developed eosinophilia. The incidence of eosinophilia in Group I was significantly greater (93.7%) than in Group iII infants
EOSINOPHILIA IN GROUP~ PREMATURE INFANTS
(Mean •
5000
and Range)
Birthweighl l regained
4000 3000:
Mean
2500 E
I Range
2> 2 0 0 0 o J= o
4:::
:::i1111111[
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"~ 1000 ~::jiiiilili!
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4'0
5'0
Age of premature infanls (days)
8'0
Fig. 2. Mean, standard deviation (shaded area), and range of serial AEC in Group II infants. Number of infants = 13. Age when eosinophilia started--13 +_ 4.9 days (mean +_ SD); age when eosinophilia peaked--21 _+ 5.1 days; duration of eosinophilia-26 -+ 16.6 days; age when birth weight regained--20 • 11 days.
(56.2%), with P value 0.01. The incidence of mild eosinophilia was higher in Group III (55.5%) than in Group l (6.6%) infants, with P value 0.025. However, the incidence of severe eosinophilia was significantly higher ( P - - 0 . 0 0 8 ) in Group I (40%) than in Group III (0%) infants.
6 14
Bhat and Scanlon
The Journal of Pediatrics April 1981
EOSINOPHILIA IN GROUP I]I PREMATURE INFANTS (Mean { S D and Range) 2000
r
1500~-
,ooo I
Bir thweiqht 1 regained
]
-
~an nge
E 800
=
c
._
600-
400-
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Age of premature infants (days)
,'o
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Fig. 3. Mean, standard deviation (shaded area), and range of serial AEC in Group II1 infants. Number of infants = 16. Age when eosinophilia started--13.8 • 8.3 days (mean 4- SD); age when eosinophilia peaked-18.8 4- 8.1 days; duration of eosinophilia-9.7 4- 8 days; age when birth weight regained--9.9 +_ 5.5 days.
lnwihllnswih I
Table. Comparison of clinical course and different variables in infants with or without eosinophilia
D(~erent variables
no eosinophilia N = 11
eosinophilia N = 34
Infants intubated Duration of intubation in days (mean __+SD) Infants who received TPN Duration of TPN in days (mean _+ SD) Infants transfused blood Number of transfusions (mean • SD) Birth weight in gm (mean 4- SD) Weight loss in % of birth weight (mean • SD) Age (in days) when lowest (nadir) weight was reached (mean 4- SD) Age (in days) when birth weight was regained (mean • SD) Gestational age in wk (mean _+ SD) AEC at birth (No./mm ,~) (mean 4- SD) AEC at discharge (No./mm "~)(mean • SD)
3 (27.2%) 1.6 • 1.1 3 (27.2%) 6.6 _+ 8.1 6 (54.5%) 3.6 4- 3.2 1,510 • 277 3.1 4- 4.6 3.7 4- 3.6 9.8 4- 6.4 32.6 4- 2.5 82 4- 32.5 273 _+ 168
24 (70.5%) 7.9 • 10 24 (70.5%) 26.5 • 28.7 32 (94.1%) 9.4 _+ 8.3 1,302 • 352 10.7 • 6.0 6.5 • 3.8 18 4- 8.8 30,7 4- 23' 105 • 80 361 • 312
(P 0.01)*
(P 0.001)*
P value
0.025 0.001
0.025 0.001 0.0025 0.05 0.02 0.02 0.05 0.01 0.02 NS NS
Statistical analysis was performed by t test and Chi square using Yates correction. N = Number of babies; NS = nonsignificant. *Comparing AEC at birth and discharge. Figs. 1, 2, and 3 illustrate the pattern of eosinophilia for the three weight groups. The age at onset of eosinophilia did not differ significantly among the three groups. Peak eosinophilia occurred significantly later (P = 0.01) in Group I than in either Group II or Group III infants. The duration of eosinophilia was similarly significantly longer in Group I than in either Group II or Group III infants. The A E C at birth was significantly lower than at discharge in all three weight groups. The age when eosinophilia started was not significantly different in infants with mild, moderate, or severe eosino-
philia: 17 _+ 7.9, 12.2 +_+_4.9, and 12.2 • 5.2 days (mean -+ SD), respectively. However, eosinophilia peaked at 30 • 6.1 days (mean ___ SD) in infants with severe eosinophilia, significantly later (P = 0.01) than in infants with moderate eosinophilia (22.4 __+ 5 days i and in those with mild eosinophilia (!8. ! _+ 9.1 days), with P value 0.001. Similarly, the duration of eosinophilia was significantly longer (P = 0.001) in infants with severe eosinophilia (64.5 • 18.6 days) than with moderate eosinophilia (27.8 • 16.4 days) or mild eosinophilia (6.7 • 6.4 days). There was no significant difference between A E C
Volume 98 Number 4
at birth and at discharge in infants with mild eosinophilia, but the AEC at birth in infants with moderate and Severe eosinophilia was significantly lower than at discharge. Endotraeheal intubation and eosinophilia (Table). The number of infants intubated and the duration of intubation were significantly greater in infants with eosinophilia than in those with no eosinophilia. The number of intubations was similar in infants with mild, moderate, and severe eosinophilia. However, the duration of intubation was significantly longer (P < 0.05) for infants with severe than in those with either moderate or mild eosinophilia. This finding is consistent with their being smaller and less mature. Nutrition and eosinophilia (Table). Twenty-seven infants received supplemental TPN (13 received TPN plus human milk and 14 received TPN plus human milk plus formula) and 24 (88.8%) of them developed eosinophilia. Eighteen infants did not get TPN (four received only human milk, seven received only formula, and seven received both); ten of these (55.5%) developed e0sinophilia. A significantly higher number of infants who received TPN developed eosinophilia (P < 0.02). The duration of TPN was significantly higher in infants with eosinophilia. The number of infants who received TPN was significantly higher (P < 0.04) among those with moderate than in those with mild eosinophilia. Similarly, significantly more infants (P < 0.025) with severe than with mild eosinophilia received TPN. The duration of TPN was also significantly longer (P < 0.01) in infants with severe and moderate than in those with mild eosinophilia. No significant difference was fourd in the incidence of eosinophilia between breast-fed and formula-fed infants. However, the number of infants was small. Blood transfusions and eosinophilia (Table). The number of infants who received blood transfusions as well as the frequency of these transfusions was significantly h!gher in infants with eosinophilia. Infants with severe or moderate eosinophilia received significantly more (P < 0.001) blood transfusions than those who had mild eosinophilia. Weight loss or gain and eosinophilia (Table). Birth weight was significantly lower in infants with eosinophilia. The amount of weight loss and the age when weight nadir was reached were significantly h!gher in infants with eosinophilia. Infants with no eosinophilia regained their birth weight earlier than those with eosinophilia. Infants ~ith severe and moderate eosinophilia were significantly smaller and reached their nadir weight significantly later than those with mild eosinophilia. The age at the onset of eosinophilia, age at the onset of peak eosinophilia, and age when birth weight was regained in Groups I, II, and III are depicted in Figs. 1, 2, and 3. Correlation analysis was performed between age when
Pattern of eosinophilia in premature infants
6 15
birth weight was regained and age when eosinophilia started. The correlation coefficients in Groups I, II and III were r = 0.0034 (P = NS), r = 0,4372 (P = NS), and r = 0.557 (P = NS), respectively. Similar analysis was performed between age when birth weight was regained and age when e0sinophilia peaked. The correlation coefficients were r = 0.3374 (P = NS), r = 0.5222 (P = NS), and r = 0.19818 (P = NS) for Groups I, II, and III infants, respectively. Eosinophi!ia and sepsis. Five infants developed sepsis proven by positive blood culture. In each instance, the episode of sepsis significantly suppressed eosinophilia. Pre-illness AEC were regained very shortly after therapeutic intervention for sepsis. The majority of these infants developed sepsis during the resolution of eosin0philia. The occurrence of sepsis did not change either the degree of severity or the duration of eosinophilia; therefore, these infants were included in the analysis. DISCUSSION The eosinophil resembles a neutrophil in form, motility, and phagocytic capacity. Its granules contain many of the same enzymes. However, eosinophils behave differently than neutrophils in response to infection, antigenic challenge, or corticosteroid administrationY~ Infection or administration of corticosteroids causes eosinopenia, whereas the neutrophil count usually increases in response to these stimuli. Similarly, an antigenic challenge causes AEC to rise but the neutrophil count is usually not much affected. After a brief period in the circulation, the eosinophil migrates, especially to sites exposed to external materials such as the bronchus, gastrointestinal tract, and skin. 13Their overall function in human beings is not well understood but eosinophilia is a common finding in many allergic, IgE,mediated disorders? 4 It is postulated that eosinophils are involved in a primary response to various foreign antigen s . Prolonged processing of antigens at the cellular level is necessary for the developmemt of eosinophilia. I~ The AEC varies with age? Eosinophilia occurs frequently in premature infants?' ~ The process of birth changes the infant's environment from one relatively antigen free to one replete with various antigens. Antigens are potentially absorbed from the skin, upper airways, and, importantly, from the gastrointestinal tract. Newborn infants, and particularly premature infants, absorb greater quantities of ingested antigens than do older infants or adults. 1~, 17 For the premature infant this may be related to persisting primitive pinocytic process of antigen absorption present in the undeveloped small intestine. TM In a recent retrospective study, 6 no correlation was found between eosinophilia and gestational age, TPN,
6 16
Bhat and Scanlon
endotracheal intubation, or blood transfusions. A temporal relationship between e0sinophilia and weight gain was suggested. However, this study did not specifically look at infants of various gestational ages and birth weights; infants were lumped into a single group. Our study, done prospectively in three groups of infants of various gestational ages, found significant differences in the incidence, severity, and duration of eosinophilia among these grQups. The smallest infants had the highest incidence, severity, and duration of eosinophilia. We also found a significant difference in the incidence, severity and duration of eosinophilia between infants who did or did not receive TPN; all instances of severe eosinophilia occurred in infants who had received TPN. We could not separate the effects of amino acids and of lipids because all infants received both simultaneously. Blood transfusions and endotracheal intubations were also associated with eosinophilia. We could not demonstrate any relationship between weight gain and eosinophilia. Delay in attaining birth weight did not delay the onset of eosinophilia, and there was no correlation between the age when birth weight was regained with the age at onset of eosinophilia or the age at peak eosinophilia. We suggest that eosinophilia in premature infants may be one response to external antigens. This response might be mediated by maturation of barrier mechanisms in the gastrointestinal or respiratory tract or both. Foreign antigen s gain access to the body through gastrointestinal, upper airway (particularly after prolonged endotracheal , intubation), or intravenous routes. The n u m b e r of days necessary for eosinophilia to develop might be the time required for cellular antigen processing, and is probably constant in various groups of infants. This concept might explain why the onset of eosinophilia seemed relatively constant. The greater incidence, severity, and duration of eosinophilia in the less mature infants could be related to their increased exposure to more and various antigens (more TPN, blood transfusions, and endotracheal intubafions ) superimposed on immature gastrointestinal molecular absorption? ~ In our study, the onset of sepsis was consistently associate d with decline in eosinophil counts, as previously described.2. ,, 1.~Infants who did not develo p eosinophilia did not have documented infection. We conclude that sepsis is not a valid explanation why some of our infants did not develop eosinophilia, as previously suggested? The exact cause of eosinophilia in premature infants remains unclear. However, the incidence, severity, and duration of eosinophilia are higher in lower gestational age infants, in those who receive more TPN or blood
The Journal of Pediatrics April 1981
transfusions, and in those subjected to prolonged endotracheal intubation. Thus eosinophilia in the premature h u m a n may be a physiologic, albeit developmentally immature process needed to handle foreign antigen.
REFERENCES
1. MedoffHS, and Barbero AJ: Total blood eosinophil counts in the newborn period, Pediatrics 6:737, 1950. 2. Burrel JM: A comparative study of the circulating eosinophil level in babies. I. Premature infants, Arch Dis Child 27:337, 1952. 3. Xanthore M: Leucocyte blood picture in healthy full-term and premature babies during neonatal period, Arch Dis Child 45:242, 1970. 4. Gunn T, Reaman G, Outerbridge EW, and Colle E: Peripheral total parenteral nutrition for premature infants with respiratory distress syndrome: A controlled study, J PEDIATR 92:608 , 1978. 5. Church JA, Wang DW, Swanson V, Thomas D, and Sinatra F: Cows milk allergy in premature infants with hypereosinophilia and hyperimmunoglobulinemia E, Ann Allergy 41:307, 1978. 6. Gibson EL, Vaucher Y, and Corrigan J J: Eosinophilia in premature infants: Relationship to weight gain, J PEDIATR 95:99, 1979. 7. Dubowitz LMS, Dubowitz V, and Goldberg C: Clinical assessment of gestational age in newborn infants, J PED1ATR 77:1, 1970. 8. Cartwright GE: Diagnostic laboratory hematology, ed 4, New York, 1968, Grune & Stratton, Inc. p 48, 50. 9. MacFarlane JCW, and Cecil GW: Eosinophil counting: A modification of Pilot's method, Br Med J 2:1187, 1951. 10. Data on file, Becton, Dickinson and Company, Rutherford, NJ 07070. Available on request. 11. Costello RT: A UNOPETTE for eosinophil counts, Am J Clin Pathol 54:249, 1970. 12. Basten A, Boyer MH, and Beeson PB: Mechanism of eosinophilia. I. Factors affecting the eosinophil response of rats to Trichinella spiralis, J Exp Med 131:1271, 1971. 13. Rytomma T: Organ distribution and histochemical properties of eosinophil granulocytes !n the rat, Acta Pathol Microbiol Scand 50:(Suppl 140): 1, 1960. 14. Beeson PB, and Bass DA: The eosinophil, Philadelphia, 1977, WB Saunders Company, pp 161-189. 15. Walls RS, and Beeson PB: Mechanism of eosinophils. VIII. Importance of local cellular reactions in stimulating eosinophil production, Clin Exp Immunol 12:11 I, 1972. 16. Grusky FL, and Rosario B: The gastrointestinal absorption of unaltered protein in normal infants and infants recovering from diarrhea, Pediatrics 16:763, 1955. 17. Rothbert RM: lmmunoglobulin and specific antibody synthesis during the first weeks of life of premature infants, J PEDIATR75:391, 1969. 18. Clark SL: The ingestion of proteins an d colloidal materials by Columner epithelia cells of the small intestine in suckling rats and mice, J Biophys Biochem Cytol 5:41, 1959. 19. BassDA: Behavior of eosinophil leukocytes in acute inflammation. II. Eosinophil dynamics during acute inflammation, J Clin Invest 56:870, 1975.
April 1981 The Journal of P E D I A T R I C S
The pattern of eosinophilia in premature infants A prospective study in premature infants using the absolute eosinophil count
The incidence and severity of eosinophilia was prospectively studied in 45 premature infants, who were divided into three groups according to their gestational age, The incidence and severity of eosinophilia was higher in smaller preterm infants. A significantly higher number of infants with eosinophilia received total parenteral nutrition, endotracheal intubation, or blood transfusions. The duration of total parenteral nutrition or endotracheal intubation and the number of blood transfusions were also significantly higher in infants with eosinophilia. Eosinophilia in premature infants is not associated with neutropenia.
Abdul M. Bhat, M.B.B.S.,* and John W. Scanion, M.D., Washington, D.C.
EOSINOPHILIA occurs frequently in premature infants ~-'~ but the mechanism has not been elucidated. Eosinophilia has been associated with total parenteral nutrition s and with cow milk allergy in premature infants? In a retrospective study, Gibson et aP found eosinophilia to be associated with an anabolic state in preterm infants; infants had eosinophilia only after steady weight gain was established, and there was no relationship between gestational age and degree of eosinophilia. We undertook a prospective study of the incidence of eosinophitia in premature infants to detect differences in the incidence, severity, and duration of eosinophilia among infants of various gestational ages and birth weights. This study also investigated the relationship between total parenteral nutrition or oral nutrition (human milk or formula) and eosinophilia. Other clinical phenomena were also analyzed for their relationship with the onset, incidence, and severity of eosinophilia.
MATERIAL AND M E T H O D S From September, 1979, to March, 1980, 45 preterm infants below 37 weeks' gestationaI age were admitted to
From the Division of Neonatology, Columbia Hospital for Women, and Department of Pediatrics (Neonatology), Georgetown University Hospital Supported by a grant from the Research Foundation of The Columbia Hospital for Women. *Reprint address: Division of Neonatology, Hurley Medical Center, Number One Hurley Plaza, Flint, MI 48502. VoL 98, No. 4, pp. 612-616
our nurseries and eligible for the study. The gestational age of all subjects was estimated by the method of Dubowitz et al. 7 Infants with congenital abnormalities, those small for gestational age, twins, and those receiving corticosteroids were excluded, Abbreviations used AEC: absolute eosinophil count TPN: total parenteral nutrition ET: endotracheal For analysis, 45 appropriate for gestational age infants were divided into three groups based on gestational age. Group I was comprised of 16 infants at 30 weeks or below (27.4 • 1.45 mean -_+ SD); their weights varied from 780 to 1,200 gm (942 • 139). Group II was comprised of 13 infants between 31 and 33 weeks (31.7-4-0.69); their weights varied from 1,300 to 1,540 gm (1,391-+-89). Group I l i was comprised of 16 infants between 34 and 36 weeks (34.2 • 0.54); their weights varied f r o m 1,540 to 1,880 gm (1,704 _+ 87). Absolute eosinophil count was done with the UNOPETTE, test 5877 system (Beckton Dickinson and Company, Rutherford, N. J.). This procedure uses a modified Pilot solution containing phloxine B as the selective stain for eosinophils? Propylene, glycol, incorporated in the diluent, acts as the vehicle for the phloxine B stain and renders erythrocytes relatively nonrefractile so they do not interfere with the visual counting procedure. 9 AEC determined this way compares favorably with that determined 0022-3476/81/040612+05500.50/0 9 1981 The C. V. Mosby Co.
Pattern of eosinophiiia in premature infants
Volume 98 Number 4
6 13
EOSINOPHILIA IN GROUP I PREMATURE INFANTS (Mgan ~ $ 0 and Range) Birthweight regained - Mean
8O00 7000
I Range
500, E
"-- 4 0 0 , "E o
~
&!iiill
300(
=o
/
~, 2 0 0 0 "S
;;i';i;
~i :ii
~ooo
iiiii
~
~
9 I
0
I;
20
+sD
<:
-2o 'Age of p r e m a l u r e
5'0
r
infants
I
8'o
L
9o
,oo
(days)
Fig. 1. Mean, standard deviation (shaded area), and range Of serial AEC in Group I infants. Number of infants = 16. Age when eosinophilia started-13.3 +_ 5.3days (mean • SD); age when eos!nophilia peaked-27.4 • 5.6 days; duration of eosinophilia--44.6 • 26.8 days; agewhen birth weight regained-2L2 • 7.4 days.
by the Thoma-White cell pipette using a modified Pilot solution? ~ " This procedure is more accurate and precise than an eosinophil count estimated from a peripheral blood smear. All eosinophil counts were performed by one of the authors (A. M. B.) to ensure similar methods and consistency in counting. Eosinophilia was defined ~ as an absolute eosinophil count more than 700/mint Mild eosinophilia was defined as an AEC between 700 and 999/mm:~; 1,000 to 2,999/ mm 3 was classified as moderate; more than 3,000/mm" was considered9to be severe eosinophilia. All infants had an AEC performed within 24 hours after birth, then twice weekly until discharge. Their weight, length, head circumference, number of blood transfusions, duration of endotracheal intubation, and nutritional intake (type and volume) were carefully recorded. Any significant clinical events occurring during the nursery stay were noted. Statistical analysis on parametric data was done using the Student t test or correlation analysis. Nonparametric data were analyzed by X= with Yates correction or the Fisher exact test. The clinical study was approved by the Human Research Committee of Georgetown University Hospital. Written informed consent was obtained from all parents. RESULTS Thirty-four (75.5%) of 45 infants studied developed eosinophilia. The incidence of eosinophilia in Group I was significantly greater (93.7%) than in Group iII infants
EOSINOPHILIA IN GROUP~ PREMATURE INFANTS
(Mean •
5000
and Range)
Birthweighl l regained
4000 3000:
Mean
2500 E
I Range
2> 2 0 0 0 o J= o
4:::
:::i1111111[
........: i!!!!iiiliiil
1500
"~ 1000 ~::jiiiilili!
......
50O
0
]
0
I0
20
I
50
i ),IT +s 4,
4'0
5'0
Age of premature infanls (days)
8'0
Fig. 2. Mean, standard deviation (shaded area), and range of serial AEC in Group II infants. Number of infants = 13. Age when eosinophilia started--13 +_ 4.9 days (mean +_ SD); age when eosinophilia peaked--21 _+ 5.1 days; duration of eosinophilia-26 -+ 16.6 days; age when birth weight regained--20 • 11 days.
(56.2%), with P value 0.01. The incidence of mild eosinophilia was higher in Group III (55.5%) than in Group l (6.6%) infants, with P value 0.025. However, the incidence of severe eosinophilia was significantly higher ( P - - 0 . 0 0 8 ) in Group I (40%) than in Group III (0%) infants.
6 14
Bhat and Scanlon
The Journal of Pediatrics April 1981
EOSINOPHILIA IN GROUP I]I PREMATURE INFANTS (Mean { S D and Range) 2000
r
1500~-
,ooo I
Bir thweiqht 1 regained
]
-
~an nge
E 800
=
c
._
600-
400-
z~::~ ....... /qil;i............. :i) t. i]ii::iii::iii] . . . i) :::::::::::::::::::::::
"Q<~Om 200-~ ~iiii~i:iii0 ~ili.:iii!ilii:i:i:iiiIi:.:.:.:.:.:.: Ju 0
5
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,;
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Age of premature infants (days)
,'o
&
5'o
Fig. 3. Mean, standard deviation (shaded area), and range of serial AEC in Group II1 infants. Number of infants = 16. Age when eosinophilia started--13.8 • 8.3 days (mean 4- SD); age when eosinophilia peaked-18.8 4- 8.1 days; duration of eosinophilia-9.7 4- 8 days; age when birth weight regained--9.9 +_ 5.5 days.
lnwihllnswih I
Table. Comparison of clinical course and different variables in infants with or without eosinophilia
D(~erent variables
no eosinophilia N = 11
eosinophilia N = 34
Infants intubated Duration of intubation in days (mean __+SD) Infants who received TPN Duration of TPN in days (mean _+ SD) Infants transfused blood Number of transfusions (mean • SD) Birth weight in gm (mean 4- SD) Weight loss in % of birth weight (mean • SD) Age (in days) when lowest (nadir) weight was reached (mean 4- SD) Age (in days) when birth weight was regained (mean • SD) Gestational age in wk (mean _+ SD) AEC at birth (No./mm ,~) (mean 4- SD) AEC at discharge (No./mm "~)(mean • SD)
3 (27.2%) 1.6 • 1.1 3 (27.2%) 6.6 _+ 8.1 6 (54.5%) 3.6 4- 3.2 1,510 • 277 3.1 4- 4.6 3.7 4- 3.6 9.8 4- 6.4 32.6 4- 2.5 82 4- 32.5 273 _+ 168
24 (70.5%) 7.9 • 10 24 (70.5%) 26.5 • 28.7 32 (94.1%) 9.4 _+ 8.3 1,302 • 352 10.7 • 6.0 6.5 • 3.8 18 4- 8.8 30,7 4- 23' 105 • 80 361 • 312
(P 0.01)*
(P 0.001)*
P value
0.025 0.001
0.025 0.001 0.0025 0.05 0.02 0.02 0.05 0.01 0.02 NS NS
Statistical analysis was performed by t test and Chi square using Yates correction. N = Number of babies; NS = nonsignificant. *Comparing AEC at birth and discharge. Figs. 1, 2, and 3 illustrate the pattern of eosinophilia for the three weight groups. The age at onset of eosinophilia did not differ significantly among the three groups. Peak eosinophilia occurred significantly later (P = 0.01) in Group I than in either Group II or Group III infants. The duration of eosinophilia was similarly significantly longer in Group I than in either Group II or Group III infants. The A E C at birth was significantly lower than at discharge in all three weight groups. The age when eosinophilia started was not significantly different in infants with mild, moderate, or severe eosino-
philia: 17 _+ 7.9, 12.2 +_+_4.9, and 12.2 • 5.2 days (mean -+ SD), respectively. However, eosinophilia peaked at 30 • 6.1 days (mean ___ SD) in infants with severe eosinophilia, significantly later (P = 0.01) than in infants with moderate eosinophilia (22.4 __+ 5 days i and in those with mild eosinophilia (!8. ! _+ 9.1 days), with P value 0.001. Similarly, the duration of eosinophilia was significantly longer (P = 0.001) in infants with severe eosinophilia (64.5 • 18.6 days) than with moderate eosinophilia (27.8 • 16.4 days) or mild eosinophilia (6.7 • 6.4 days). There was no significant difference between A E C
Volume 98 Number 4
at birth and at discharge in infants with mild eosinophilia, but the AEC at birth in infants with moderate and Severe eosinophilia was significantly lower than at discharge. Endotraeheal intubation and eosinophilia (Table). The number of infants intubated and the duration of intubation were significantly greater in infants with eosinophilia than in those with no eosinophilia. The number of intubations was similar in infants with mild, moderate, and severe eosinophilia. However, the duration of intubation was significantly longer (P < 0.05) for infants with severe than in those with either moderate or mild eosinophilia. This finding is consistent with their being smaller and less mature. Nutrition and eosinophilia (Table). Twenty-seven infants received supplemental TPN (13 received TPN plus human milk and 14 received TPN plus human milk plus formula) and 24 (88.8%) of them developed eosinophilia. Eighteen infants did not get TPN (four received only human milk, seven received only formula, and seven received both); ten of these (55.5%) developed e0sinophilia. A significantly higher number of infants who received TPN developed eosinophilia (P < 0.02). The duration of TPN was significantly higher in infants with eosinophilia. The number of infants who received TPN was significantly higher (P < 0.04) among those with moderate than in those with mild eosinophilia. Similarly, significantly more infants (P < 0.025) with severe than with mild eosinophilia received TPN. The duration of TPN was also significantly longer (P < 0.01) in infants with severe and moderate than in those with mild eosinophilia. No significant difference was fourd in the incidence of eosinophilia between breast-fed and formula-fed infants. However, the number of infants was small. Blood transfusions and eosinophilia (Table). The number of infants who received blood transfusions as well as the frequency of these transfusions was significantly h!gher in infants with eosinophilia. Infants with severe or moderate eosinophilia received significantly more (P < 0.001) blood transfusions than those who had mild eosinophilia. Weight loss or gain and eosinophilia (Table). Birth weight was significantly lower in infants with eosinophilia. The amount of weight loss and the age when weight nadir was reached were significantly h!gher in infants with eosinophilia. Infants with no eosinophilia regained their birth weight earlier than those with eosinophilia. Infants ~ith severe and moderate eosinophilia were significantly smaller and reached their nadir weight significantly later than those with mild eosinophilia. The age at the onset of eosinophilia, age at the onset of peak eosinophilia, and age when birth weight was regained in Groups I, II, and III are depicted in Figs. 1, 2, and 3. Correlation analysis was performed between age when
Pattern of eosinophilia in premature infants
6 15
birth weight was regained and age when eosinophilia started. The correlation coefficients in Groups I, II and III were r = 0.0034 (P = NS), r = 0,4372 (P = NS), and r = 0.557 (P = NS), respectively. Similar analysis was performed between age when birth weight was regained and age when e0sinophilia peaked. The correlation coefficients were r = 0.3374 (P = NS), r = 0.5222 (P = NS), and r = 0.19818 (P = NS) for Groups I, II, and III infants, respectively. Eosinophi!ia and sepsis. Five infants developed sepsis proven by positive blood culture. In each instance, the episode of sepsis significantly suppressed eosinophilia. Pre-illness AEC were regained very shortly after therapeutic intervention for sepsis. The majority of these infants developed sepsis during the resolution of eosin0philia. The occurrence of sepsis did not change either the degree of severity or the duration of eosinophilia; therefore, these infants were included in the analysis. DISCUSSION The eosinophil resembles a neutrophil in form, motility, and phagocytic capacity. Its granules contain many of the same enzymes. However, eosinophils behave differently than neutrophils in response to infection, antigenic challenge, or corticosteroid administrationY~ Infection or administration of corticosteroids causes eosinopenia, whereas the neutrophil count usually increases in response to these stimuli. Similarly, an antigenic challenge causes AEC to rise but the neutrophil count is usually not much affected. After a brief period in the circulation, the eosinophil migrates, especially to sites exposed to external materials such as the bronchus, gastrointestinal tract, and skin. 13Their overall function in human beings is not well understood but eosinophilia is a common finding in many allergic, IgE,mediated disorders? 4 It is postulated that eosinophils are involved in a primary response to various foreign antigen s . Prolonged processing of antigens at the cellular level is necessary for the developmemt of eosinophilia. I~ The AEC varies with age? Eosinophilia occurs frequently in premature infants?' ~ The process of birth changes the infant's environment from one relatively antigen free to one replete with various antigens. Antigens are potentially absorbed from the skin, upper airways, and, importantly, from the gastrointestinal tract. Newborn infants, and particularly premature infants, absorb greater quantities of ingested antigens than do older infants or adults. 1~, 17 For the premature infant this may be related to persisting primitive pinocytic process of antigen absorption present in the undeveloped small intestine. TM In a recent retrospective study, 6 no correlation was found between eosinophilia and gestational age, TPN,
6 16
Bhat and Scanlon
endotracheal intubation, or blood transfusions. A temporal relationship between e0sinophilia and weight gain was suggested. However, this study did not specifically look at infants of various gestational ages and birth weights; infants were lumped into a single group. Our study, done prospectively in three groups of infants of various gestational ages, found significant differences in the incidence, severity, and duration of eosinophilia among these grQups. The smallest infants had the highest incidence, severity, and duration of eosinophilia. We also found a significant difference in the incidence, severity and duration of eosinophilia between infants who did or did not receive TPN; all instances of severe eosinophilia occurred in infants who had received TPN. We could not separate the effects of amino acids and of lipids because all infants received both simultaneously. Blood transfusions and endotracheal intubations were also associated with eosinophilia. We could not demonstrate any relationship between weight gain and eosinophilia. Delay in attaining birth weight did not delay the onset of eosinophilia, and there was no correlation between the age when birth weight was regained with the age at onset of eosinophilia or the age at peak eosinophilia. We suggest that eosinophilia in premature infants may be one response to external antigens. This response might be mediated by maturation of barrier mechanisms in the gastrointestinal or respiratory tract or both. Foreign antigen s gain access to the body through gastrointestinal, upper airway (particularly after prolonged endotracheal , intubation), or intravenous routes. The n u m b e r of days necessary for eosinophilia to develop might be the time required for cellular antigen processing, and is probably constant in various groups of infants. This concept might explain why the onset of eosinophilia seemed relatively constant. The greater incidence, severity, and duration of eosinophilia in the less mature infants could be related to their increased exposure to more and various antigens (more TPN, blood transfusions, and endotracheal intubafions ) superimposed on immature gastrointestinal molecular absorption? ~ In our study, the onset of sepsis was consistently associate d with decline in eosinophil counts, as previously described.2. ,, 1.~Infants who did not develo p eosinophilia did not have documented infection. We conclude that sepsis is not a valid explanation why some of our infants did not develop eosinophilia, as previously suggested? The exact cause of eosinophilia in premature infants remains unclear. However, the incidence, severity, and duration of eosinophilia are higher in lower gestational age infants, in those who receive more TPN or blood
The Journal of Pediatrics April 1981
transfusions, and in those subjected to prolonged endotracheal intubation. Thus eosinophilia in the premature h u m a n may be a physiologic, albeit developmentally immature process needed to handle foreign antigen.
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1. MedoffHS, and Barbero AJ: Total blood eosinophil counts in the newborn period, Pediatrics 6:737, 1950. 2. Burrel JM: A comparative study of the circulating eosinophil level in babies. I. Premature infants, Arch Dis Child 27:337, 1952. 3. Xanthore M: Leucocyte blood picture in healthy full-term and premature babies during neonatal period, Arch Dis Child 45:242, 1970. 4. Gunn T, Reaman G, Outerbridge EW, and Colle E: Peripheral total parenteral nutrition for premature infants with respiratory distress syndrome: A controlled study, J PEDIATR 92:608 , 1978. 5. Church JA, Wang DW, Swanson V, Thomas D, and Sinatra F: Cows milk allergy in premature infants with hypereosinophilia and hyperimmunoglobulinemia E, Ann Allergy 41:307, 1978. 6. Gibson EL, Vaucher Y, and Corrigan J J: Eosinophilia in premature infants: Relationship to weight gain, J PEDIATR 95:99, 1979. 7. Dubowitz LMS, Dubowitz V, and Goldberg C: Clinical assessment of gestational age in newborn infants, J PED1ATR 77:1, 1970. 8. Cartwright GE: Diagnostic laboratory hematology, ed 4, New York, 1968, Grune & Stratton, Inc. p 48, 50. 9. MacFarlane JCW, and Cecil GW: Eosinophil counting: A modification of Pilot's method, Br Med J 2:1187, 1951. 10. Data on file, Becton, Dickinson and Company, Rutherford, NJ 07070. Available on request. 11. Costello RT: A UNOPETTE for eosinophil counts, Am J Clin Pathol 54:249, 1970. 12. Basten A, Boyer MH, and Beeson PB: Mechanism of eosinophilia. I. Factors affecting the eosinophil response of rats to Trichinella spiralis, J Exp Med 131:1271, 1971. 13. Rytomma T: Organ distribution and histochemical properties of eosinophil granulocytes !n the rat, Acta Pathol Microbiol Scand 50:(Suppl 140): 1, 1960. 14. Beeson PB, and Bass DA: The eosinophil, Philadelphia, 1977, WB Saunders Company, pp 161-189. 15. Walls RS, and Beeson PB: Mechanism of eosinophils. VIII. Importance of local cellular reactions in stimulating eosinophil production, Clin Exp Immunol 12:11 I, 1972. 16. Grusky FL, and Rosario B: The gastrointestinal absorption of unaltered protein in normal infants and infants recovering from diarrhea, Pediatrics 16:763, 1955. 17. Rothbert RM: lmmunoglobulin and specific antibody synthesis during the first weeks of life of premature infants, J PEDIATR75:391, 1969. 18. Clark SL: The ingestion of proteins an d colloidal materials by Columner epithelia cells of the small intestine in suckling rats and mice, J Biophys Biochem Cytol 5:41, 1959. 19. BassDA: Behavior of eosinophil leukocytes in acute inflammation. II. Eosinophil dynamics during acute inflammation, J Clin Invest 56:870, 1975.