Cerebrospinal fluid and the choroid plexus during acute immune complex disease

CLINICAL

IMMUNOLOGY

AND

IMMUNOPATHOLOGY

13,413-425

(1979)

Cerebrospinal Fluid and the Choroid Plexus during Acute Immune Complex Disease’ RONALD J. HARBECK,

ANDREE A. HOFFMAN, STEVEN A. HOFFMAN, AND DAVID WM. SHUCARD

The Division of Allergy and Clinical Immunology. Department of Medicine. Brain Sciences Lahoratorirs. Department of Behavioral Sciences, National Hospital and Research Center, Denver, Colorudo 80206

and the Jewish

Received January 16, 1979 During acute immune complex disease in the rabbit, immune deposits could be detected in the choroid plexus, as well as the kidney, in a majority of the animals sacrificed from 9 to 14 days after the injection of bovine serum albumin (BSA). During this time there was a good correlation between deposits in the choroid plexus and increases in cerebrospinal fluid (CSF) albumin and IgG. A relatively unchanged CSF IgG to albumin ratio was observed, while the CSF to serum albumin level was increased, suggesting an alteration in the blood-CSF barrier permeability to serum proteins. In addition, the temporal appearance of BSA and anti-BSA in the CSF of these animals mirrored their appearance in the serum and in one animal immune complexes could be detected in the CSF. The significance of these results is discussed in relation to the pathogenesis of central nervous system (CNS) disease in systemic lupus erythematosus (SLE).

INTRODUCTION

Experimental immune complex disease induced in the rabbit with bovine serum albumin (BSA) has been used as a model of glomerulonephritis for a number of years (1). In acute experimental immune complex disease or one-shot serum sickness, induced in rabbits by a single large injection of BSA, circulating immune complexes become localized in several organs, including the kidney. This results in glomerular inflammatory injury and functional impairment. The systemic involvement in experimental immune complex disease in many ways resembles that observed in the human condition of systemic lupus erythematosus (SLE), a disease in which immune complex deposition has been implicated in the pathogenesis (2). One of the more critical and life-threatening manifestations of SLE is the central nervous system (CNS) involvement (3). Although little is known of the etiology and pathogenic mechanisms mediating CNS disturbances in SLE, several lines of evidence point to an immunologic involvement. Among these are the findings that immune complex deposition can be seen in the choroid plexus in naturally occurring immune complex diseases in patients with SLE, in New Zealand mice, and in lambs with mesangiocapillary glomerulonephritis (4- 8). Furthermore, the induction of experimental immune complex disease has also been shown to result in the occurrence of immune complexes in the choroid plexus (9- 13). The choroid plexus, a structure responsible for cerebrospinal fluid (CSF) production and filtration, is antigenically, structurally, and functionally similar to the ’ Supported by National Institutes of Health Grant NS-12394. 413 0090-1229/79/O&3413-13$01.00/0 Copyright All rights

0 1979 by Academic Press. Inc. of reproduction in any form reserved.

414

HARBECK

ET

AL.

renal glomerulus (14- 16). It is possible that the deposition of immune complexes in this structure could give rise to functional damage to the blood-CSF barrier and produce alterations in the CSF by a mechanism analogous to that occurring in immune complex mediated renal disease. The studies reported here indicate that during acute immune complex disease in the rabbit changes in CSF protein concentrations occur, possibly as a consequence of a breach in the blood-CSF barrier. In another aspect of this study, the temporal appearance of BSA, antibody to BSA, and, in one case, immune complexes in the CSF during acute immune complex disease reflects their occurrence in the serum. MATERIALS

AND

METHODS

Induction of acute immune complex disease. New Zealand white rabbits, obtained from a local commercial breeder and weighing between 2.4 and 3.6 kg, were given a single intravenous injection of 250 mg/kg BSA and a subcutaneous injection of 10 mg/kg of BSA incorporated in Freund’s complete adjuvant (9). At various times after injection, animals were anesthetized with Nembutal, exsanguinated by cardiac puncture, and the brain, kidney, and CSF removed. The CSF was removed by exposing and puncturing the cisternae magna and withdrawing the CSF with a syringe. CSF contaminated with blood, as determined by microscopic examination, was discarded. The CSF constituents of experimental animals were compared with animals injected with saline and sacrificed 14 days later. Rabbits were eliminated from further study if light microscopic examination of stained brain sections showed granuloma formation and perivascular cuffing, suggesting infection with Encephalitozoan cunicufi (17), or if preinjected rabbits had elevations in blood urea nitrogen. Immunojluorescence. The choroid plexus and kidney were removed, frozen, and sectioned at 4 pm. Kidneys were stained with the IgG fraction of fluoresceinated goat anti-rabbit y-globulin, anti-C3, or rabbit anti-BSA (Cappel Laboratories, Downingtown, Pa.), while the choroid plexus of each animal was stained with anti-BSA, anti-C3, and anti-rabbit IgG (heavy chain specific) (Cappel Laboratories, Downingtown, Pa.). A high level of background fluorescence was seen in the choroid plexus when stained with fluoresceinated goat anti-rabbit y-globulin, even after repeated absorptions with rabbit liver and brain powder. These problems were lessened by the use of an anti-rabbit IgG reagent. The stained sections were examined with a Leitz Ortholux fluorescence microscope equipped with an Osram HBO 100 W, high-pressure mercury vapor lamp and the intensity and amount of immunofluorescence arbitrarily graded on a scale from 0 (negative) to 4+ (bright, heavy deposits throughout all glomeruli and choroid plexus). Assessment was carried out by two investigators independently. IgG and albumin levels in the CSF and serum. CSF and serum IgG and albumin concentrations were measured by a modification of a sensitive electroimmunodiffusion (EID) technique (18). Two microliters of CSF or diluted serum (1:200) were electrophoresed in duplicate for the simultaneous presence of albumin and IgG on an agar-agarose gel plate containing the appropriate monospecific antisera to both proteins (Cappel Laboratories). Serum and CSF anti-BSA levels. The binding of rabbit serum to 0.04 pg N/ml

CSF

DURING

ACUTE

IMMUNE

COMPLEX

DISEASE

415

of ‘““I-la&M BSA was assayed at a l:lO.dilution utilizing an ammonium sulfate precipitation assay (19). For CSF, 50 ~1 of a 1:2 dilution of CSF was mixed with 50 ~1 of 0.04 pg N/ml 12”1-labeled BSA in 0.1 M borate-buffered saline containing 1% normal rabbit serum (NRS). Following an overnight incubation, 5 ~1 of undiluted NRS was added to the mixture followed by 105 ~1 of 50% saturated ammonium sulfate. The precipitate was obtained by centrifugation, counted, and the percentage of antigen precipitated determined (%P). Concentration of serum and CSF BSA. The ammonium sulfate inhibition assay was performed to determine the ability of serum or CSF to inhibit the binding of 12”1-labeled BSA to a rabbit anti-BSA serum (19). The results are expressed as the percentage inhibition by either a 1:20 dilution of serum or a I:2 dilution of CSF. Immune complex detection. The occurrence and amount of immune complexes in the serum and CSF of rabbits were determined by using the Raji cell radioimmunoassay technique (20). Briefly, 25 ~1 of a 1:4 dilution of serum in saline, or 25 ~1 of CSF containing NRS at a final concentration of 1:4, was added to 2 x 10” cells contained in 50 ~1 of Spinner’s medium (Grand Island Biologicals, Grand Island, New York). After a 45-min incubation at 37°C with periodic mixing, the cells were washed three times with Spinner’s medium. The cells contained in 50 ~1 of 1% rabbit serum albumin (RSA) in Spinner’s medium were then reacted with 25 ~1 of an optimal amount of a ‘““I-labeled IgG fraction of goat anti-rabbit y-globulin diluted in 1% RSA. This was incubated for 30 min at 4°C with gentle shaking. The cells were washed three times with Spinner’s containing 1% RSA and the radioactivity in the cell pellet counted. The amount of radioactive uptake in the cell pellet was compared to a standard curve of radioactive antibody uptake in which varying, known concentrations of heat-aggregated rabbit IgG were used. The amount of complexes were expressed as micrograms aggregated rabbit IgG/milliliter (ARG) of serum or CSF. By this method, immune complexes in excess of 50 pug/ml could be detected. Statistical analysis. Significance was determined by using a Student’s t test or Fisher’s exact probability analysis (21). RESULTS

Presence of Immune Complexes in Tissues Deposition of immune complexes, as demonstrated by staining for y-globulin, BSA, and/or C3, could be detected in the kidneys of the majority of animals beginning 9 days after receiving a single large dose of BSA (Table 1 and Fig. IA). Although granular deposits of y-globulin and C3 could be observed at this time, BSA was infrequently detected. By Day 12 and through Day 14, most animals of the groups showed the presence of granular deposits of BSA, y-globulin, and C3 in the kidney. In contrast, only one animal of the control group showed the unexplained appearance of C3 in its renal glomeruli. In a similar manner, immune complexes could be detected in the choroid plexus in a few animals sacrificed 9 days after receiving BSA, with a greater incidence of deposition occurring at times following this (Table 1 and Fig. 1B). The deposits in the choroid plexus were generally less discernible, being more scattered and focal in nature and staining less intensely than those observed in the kidney (Fig. 2). As determined by the Fisher test, a good correlation (P < 0.01) was observed be-

416

HARBECK

ET

TABLE APPEARANCE

OF IMMUNE

COMPLEX

AL.

1

DEPOSITION

IN THE

TISSUES OF

IMMUNE

COMPLEX

DISEASE

OF ACUTE

RABBITS

AFTER

INDUCTION

Tissue Kidney

Choroid plexus

Days after BSA

BSA

r-Globulin

Control” 6 9 12 14 18

0/14h O/6 116 315 B/11 215

0114 O/6 416 415 9111 515

c3

BSA

W

C3

1114 216 616 515 8111 515

0114 016 116 215 5112 o/5

0114 016 216 515 6111 415

0114 O/6 516 415 5112 215

n Control rabbits were sacrificed 14 days after receiving saline in place of BSA. ” Number of animals showing deposits/total number of animals tested

tween the occurrence of immune complexes in the kidney and their occurrence in the choroid plexus. Of the total of 3 1 experimental animals examined for immune complex deposits in the kidney and choroid plexus, 21 showed deposits in both tissues and 5 showed only deposits in the kidney, while 5 showed deposits neither in the choroid plexus nor in the kidney. In only one case were deposits observed in the choroid plexus and not in the kidney. Trace amounts of C3, but not BSA or IgG, were detected in the choroid plexus of this animal sacrificed 14 days after BSA injection. In none of the control animals could IgG, BSA, or C3 be detected in the choroid plexus.

4 3

1 6

9

12

14

18

DAYS

FIG. 1. Kidney and choroid plexus sections from animals sacrificed at various times after BSA administration were stained with FITC goat anti-rabbit BSA, y-globulin, or C3. The degree of immune deposits other than 0 was arbitrarily graded from 0.5 (trace amounts) to 4+ (heaviest amounts). The mean of the fluorescence intensity + SEM is given for each animal group.

CSF

DURING

ACUTE

IMMUNE

COMPLEX

DISEASE

417

418

HARBECK

ET

AL. 30

I 6

9

12 DAYS

lfl

-18

FIG. 3. The serum (GO) and CSF (0- - - 0) concentrations of albumin (mg% t- SEM) from rabbits sacrificed at various times following injection with BSA. Values for serum albumin (A) and CSF albumin (A) from control animals injected with saline and sacrificed 14 days later are shown following Day 18 values.

CSF Albumin and IgG Levels

The concentration of albumin in the CSF of 14 control rabbits, receiving only saline in adjuvant and sacrificed 14 days later, was 12.5 + 0.5 mg/dl (mean k SEM) as determined by an EID technique. This value is similar to that found in normal human CSF (16.3 +- 1.2 mg/dl) using the same technique (18). The rise in CSF albumin concentration as a function of time after a single injection of BSA is shown in Fig. 3. Levels of CSF albumin showed no significant difference, as determined by a Student’s t test, from normals at either Day 6 or Day 9 (11.8 + 1.3 mg/dl, P > 0.05, and 12.3 + 1.9 mgldl, P > 0.05, respectively); however, 12 days after the injection nearly a twofold increase in CSF albumin occurred, as compared to the normals (21.8 2 6.5 mg/dl, P < 0.05). After rising to 27.0 k 4.5 mg/dl (P < .OOl) on Day 14, the level returned to normal at Day 18 (12.5 k 1.2 mg/dl, P > 0.05). The elevation in CSF albumin was not a reflection of increased serum albumin levels (Fig. 3). The concentration of IgG in the CSF of the control animals was assessed by the EID technique to be 3.2 r 0.4 mg/dl. As was the case with CSF albumin, this value was similar to that obtained for human CSF IgG levels (2.7 + 0.2 mg/dl) (18). While no significant differences (P > 0.05) were noted in the CSF IgG levels between experimental rabbits sacrificed 6 and 9 days after receiving BSA and controls, an elevation in the mean level of CSF IgG (6.0 k 2.1 mg/dl) was detected in those animals sacrificed on Day 12 following BSA administration (Fig. 4). A highly significant (P < 0.001) elevation in CSF IgG (7.7 +- 1.3 mg/dl) was demonstrated in those animals sacrificed on Day 14. As was the situation with albumin, IgG concentrations returned to normal levels on Day 18 and as shown in Fig. 4, significant elevations in serum IgG levels did not occur. Of a total of 12 animals from the experimental groups with CSF albumin levels greater than 2 SDS above the normal mean values, all but one showed evidence of

CSF

DURING

ACUTE

IMMUNE

COMPLEX

DISEASE

419

rg

FIG. 4. The serum ( LO) and CSF (0- - -0) concentrations of IgG (mg% 2 SEM) from rabbits sacrificed at various times following injection with BSA. Values for serum (A) and CSF (A) IgG from control animals are shown following Day 18 values.

immune deposits in the choroid plexus. This is the only animal in which tissue was not available for staining for IgG; however, no deposits of BSA or C3 could be detected. While 1 of 6 of the animals sacrificed at 9 days showed this relationship, i.e., elevated CSF albumin and the occurrence of immune deposits in the choroid plexus, the incidence rose to 3 of 6 at Day 12 and to 7 of 11 by Day 14. None of the animals sacrificed at Day 6 or Day 18 showed evidence of elevation in CSF albumin or IgG. In addition, 8 of the 34 animals in all the experimental groups had CSF IgG levels greater than 2 SDS above the mean of the control group. In all but one case this was associated with deposits in the choroid plexus, this again being the same animal in which tissue was not available for staining for IgG. IgG:Albumin Ratio None of the experimental animal groups injected with BSA showed statistically significant (P > 0.05) differences from normal control animals in CSF IgG to albumin mean ratios (Table 2), although animals sacrificed 12 and 14 days after receiving BSA showed a slight increase in this ratio. In contrast, the CSF to serum albumin ratio shows a significant increase on Days 12 and 14 (Fig. 5). These results are in agreement with the belief that an increase in CSF IgG to albumin ratio which more closely approximates the normal serum ratio, as well as an increase in the CSF to serum albumin ratio, reflects an increase in the bloodbrain barrier (BBB) or blood-CSF barrier permeability to serum proteins (22,23). In contrast to the CSF a statistically significant (P < 0.01) difference in the serum IgG to albumin ratio was noted in those animals sacrificed 14 days after receiving BSA (Table 2). Several rabbits of this group had decreases in their serum albumin concentration while showing slight increases in their serum IgG levels, and the presence of significant immune complex glomerulonephritis. Hence, the alteration in serum IgG to albumin ratio may reflect a loss of serum albumin as a consequence of proteinuria.

420

HARBECK

ET AL.

TABLE CSF

CSF Serum

AND

SERUM

I~G:ALBUMIN

IN RABBITS

2 WITH

ACUTE

IMMUNE

COMPLEX

DISEASE

Controls

6 Days

9 Days

12 Days

14 Days

18 Days

0.25 5 0.02 0.30 + 0.02

0.22 -t 0.06” 0.26 2 0.04”

0.19 _f 0.02” 0.29 f 0.02”

0.27 t 0.06” 0.38 k 0.07”

0.29 + 0.02” 0.41 t 0.04”

0.24 t 0.03” 0.33 +- 0.03”

” Difference from control value, not significant. P > 0.05. ” Difference from control value. P < 0.01.

Temporal Appearance of Antigen, Antibody, and Immune Complexes in the CSF The results of examining the serum from the animals of each group for the presence of BSA, anti-BSA, and immune complexes is shown in Fig. 6. Not unexpectedly, the mean level of circulating BSA remained relatively high through 9 days after the BSA administration and showed decreased levels in the majority of animals at 12 through 18 days. In contrast, serum anti-BSA activity showed a measurable level at Day 12 and continued its rise through 18 days. Immune complexes in the serum could not be detected on Day 6 (co.05 mg/ml), occurred in four of the six animals by Day 9, and could be demonstrated in all of the animals sacrificed 12, 14, and 18 days after injection. A similar sequence of events occurred in the CSF of these rabbits (Fig. 7). A decrease in CSF BSA occurred at Day 12 following the intravenous BSA injection, and by Day 18 BSA was nearly undetectable in the CSF. Significant (P < 0.01) anti-BSA levels in the CSF was first seen in the Day 14 group of animals compared to the control group (experimentals: 18.8 + 1.6 %P; controls: 13.5 -t 0.9 %P). Of the CSF tested, using the Raji cell technique, only one animal showed immune complexes in excess of 50 &ml. The results obtained from this animal (K93) are shown in Table 3. While serum IgG levels were slightly increased (within 1 SD of the mean level of the control animals), serum albumin was not increased, resulting in an elevation in the IgG to albumin ratio. In contrast, CSF

6

9

12

15

16

DAYS FIG. 5. The CSFlserum albumin in groups of rabbits sacrificed at various times after BSA administration (GO). The CSF/serum albumin values for control rabbits receiving saline are shown to the right of Day 18 values (A).

CSF DURING

ACUTE IMMUNE

COMPLEX

DISEASE

421

DAYS

FIG. 6. The temporal appearance of anti-BSA (mean %P plexes as detected by the Raji radioimmunoassay technique the disappearance of BSA (mean % inhibition + SEM; l ficed at various times following induction of immune complex

+ SEM; q - - -0) and immune com(mg ARG eq/ml * SEM; A-A) and 0) in the sera of groups of animals sacridisease.

albumin and IgG were both well outside of 2 SDS of the control means, while the ratio of IgG to albumin in the CSF was not significantly different from normals. BSA was not demonstrated in either the serum or CSF; however, elevations in anti-BSA activity could be demonstrated in both. A high concentration of immune complexes was shown to occur in the serum of this animal as well as being found in the CSF. Furthermore, immune complex deposition could be detected in both the kidney and choroid plexus in this animal. DISCUSSION

While it has previously been shown that during experimental immune complex disease one can demonstrate immune complexes deposited in the choroid plexus (9-13), this is the first report to demonstrate other changes in the CNS, i.e., alterations in CSF protein composition. The elevations in CSF proteins, the relatively unchanged CSF IgG to albumin ratio, and the increase in the CSF to serum albumin ratio does not support the hypothesis that the IgG was produced locally

x

6 a

9

12 DAYS

15

18

FIG. 7. The temporal appearance of anti-BSA activity (mean %P 2 SEM; q - - -0) and disap pearance of BSA (mean % inhibition k SEM; L 0) from the CSF of groups of animals sacrificed at various times following induction of immune complex disease.

422

HARBECK

RABBIT

Serum K93 Normal (Mean CSF K93 Normal (Mean

k SD)

K93:

ANALYSIS

OF SERUM

TABLE AND CSF

Albumin (mg%)

IgGiAlb

1373

3593

0.38

1080

IL 278

3612

3.2 k 1.4

+ 383

AL.

3 14 DAYS

I& (mg%)

11.8 k SD)

ET

0.30

41.4

AFTER Anti-BSA (5% P)

5 .06

12.5 + 1.9

0.25

complex tissue

BSA

Kidney Choroid

plexus

2+ 2t

-16

15 k 3

2+ It

3*3

Mg ARG (eqiml)

< 0.05 3

14 t- 3

staining y-globulin

BSA

2.5

626

24

2 .08

FITC

WITH

BSA (5% inhibition)

102

0.29

Immune deposition

INJECTION

0.066 < 0.05

for c3 2t 1+

within the CNS. The data suggest instead that there was a breach in the blood-CSF barrier which allowed both albumin and IgG to pass from the serum to the CSF (22, 23). Immune complex deposits were also noted in the choroid plexus and there was a good correlation between these deposits and the increase in CSF albumin and IgG. Since the choroid plexus is thought to be responsible for the majority of CSF production, these findings suggest that immune complex deposition in this structure may have given rise to impaired secretory functioning or initiated alterations in the blood-CSF barrier integrity. It must be noted, however, that immune complex deposits in the choroid plexus were not always associated with substantial increases in CSF albumin or IgG. This was most noticeable within the Day 9 group of animals where in only one of the five animals with choroid plexus deposits could an elevation in CSF albumin be detected. In contrast, of the animals sacrificed on Day 14, six of the eight animals showing immune complex deposits had elevations in the CSF IgG and/or albumin. If the deposition of immune complexes in the choroid plexus is a significant factor in causing CSF alterations then it may be that a critical quantity of immune complexes need to be deposited before appreciable changes in choroid plexus function occur. Alternately, it may be that CSF changes are not immediate and only occur after immune complexes have been deposited within the choroid plexus for a period of time. The temporal appearance of BSA and anti-BSA in the CSF after a single large injection of BSA is reflected in their occurrence in the circulation. Immune complexes above 50 pg/ml could be demonstrated in the sera of all animals sacrificed 12, 14, and 18 days after receiving BSA. These results are consistent with a previous report which showed that during acute immune complex disease it was possible to detect immune complexes in the circulation by the Raji cell technique for a longer period of time than was possible by radiolabeling of the immune complexes (24). The possibility exists that, as in the circulation, the conditions are favorable for the formation of immune complexes within the CSF. Along these lines it has been

CSF

DURING

ACUTE

IMMUNE

COMPLEX

DISEASE

423

e xzcmpkx -fftp&tim Mds ,to rqxxwd &a& wtsdiis.d~d~~;i~ increased permeability of serous membranes and allows the accumulation of immune complexes in the exudates of rabbits with polyserositis as a consequence of immune complex disease (25). In our studies we were able to detect complexes in the CSF of one animal in which high levels of circulating complexes were present. Although not proved, the levels of anti-BSA and BSA in the serum and CSF of this animal suggest that these immune complexes are likely BSA-anti-BSA complexes. This animal also had significant deposits of immune complexes in the choroid plexus. It is difficult to differentiate between complexes diffusing through the choroid plexus from the circulation as intact complexes or as a consequence of being formed locally from free antibody and antigen in the CSF. Both mechanisms could have been facilitated by damage to the choroid plexus. The blood-brain barrier is known to be primarily manifest at the tight junctions of endothelial cells lining the vessel walls within the brain, while it is thought that the blood-CSF barrier exists as a consequence of tight junctions in the choroid plexus epithelial cells (26). Immune complexes are capable of activating complement and result in the release of vasoactive amines (2). However, cerebral capillary permeability to protein has not been shown to increase in response to histamine or serotonin (27). It is conceivable that these vasoactive substances may affect the tight epithelial junctions in the choroid plexus and result in alterations in the blood-CSF barrier. Thus, the occurrence of immune complexes within the choroid plexus may give rise to reversible functional damage to this structure in a manner analogous to the immune complex mediated damage that occurs to the kidney that results in proteinuria. In support of this is the fact that the choroid plexus and its basement membrane have been shown to be functionally, antigenitally, and structurally very similar to those of renal glomerulus (14, 16). However, our data, showing an association between immune complex deposits in the choroid plexus and increases in the CSF proteins, may be due to mechanisms other than those mediated by immune complexes. One of the more frequent and serious manifestations of SLE is CNS involvement (3). This has been reported to occur in as many as 75% of all patients with SLE (28), and in some studies it ranks as the number-one cause of death (29). Elevations in CSF total protein have been reported in as many as 50% of patients with CNS disturbance in SLE (28,30). In addition, patients with CNS disturbance of SLE have been shown to have deposits of immune complexes within the choroid plexus. Recently, neurobehavioral abnormalities have been described in a naturally occurring immune complex disease (8) and in an experimental immune complex disease (12) associated with immune deposits in the choroid plexus. Hence, it is possible that functional alterations in the choroid plexus leading to physiological CSF changes could give rise to neurobehavioral problems in SLE patients as a result of the deposition of immune complexes in the choroid plexus. Alterations in cerebrospinal fluid electrolytes and pH have been shown to affect animal behavior (3 1, 32). Additionally, it is possible that CNS disturbances occurring in SLE patients may be mediated by the local occurrence or formation of immune complexes in the CNS, resulting in a cascade of events involving complement activation, mediator release, and ultimately stimulation or inhibition of

424

HARBECK

ET AL.

neurotransmitter release. In one study, it was suggested that focal antigen-antibody reactions occurring in specific brain sites can affect the drinking behavior in rats by causing the release of norepinephrine or by interfering with normal processes involved in the cholinergic-adrenergic control of behavior (33). Anti-DNA activity, the hallmark of SLE systemic disease, has also been demonstrated in the CSF of a large number of patients with CNS-SLE. The demonstration of DNA-anti-DNA complexes in the CSF of some patients with CNSSLE may suggest a pathogenic role for these complexes (34, 35). Furthermore, support for the fact that an immune reaction may occur in the CSF of CNS-SLE patients comes from the reports of decreased complement levels in the CSF of these patients (36, 37). At least two antibodies with separate specificities are known to exist in the sera of patients with SLE (38, 39) and in the murine model of human lupus, the NZB mouse (40-42). It is of interest to speculate that these circulating antibodies may gain access to the CNS, due to permeability changes induced by immune complex deposition in the choroid plexus. Permeability changes in the choroid plexus may allow sufficient concentrations of brain reactive antibody to interact with and functionally alter CNS function. The immune complex disease model used in this report appears to be useful for studying the relationship between immune complex mediated damage to the choroid plexus and concomitant CNS changes. Such investigations will hopefully prove fruitful in helping to elucidate the role of immune complex deposition in the choroid plexus in the pathogenesis of CNS-SLE. ACKNOWLEDGMENTS We are indebted to Ms. Christine Reifenrath and Ms. Natalie Thayer for their very skillful technical assistance and Charlene Griftiths and Jan Hainbach for their skillful preparation of this manuscript.

REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9.

Unanue, E. R., and Dixon, F. J., Adwm. Immrrrzo/. 6. I. 1967. Cochrane, C. G., and Koffler, D., Advun. Inmrr~~o/. 16, 185, 1973. Gibson, T., and Myers, A. R., Ann. Rhmm. IXs. 35, 398, 1976. Atkins, G. J., Kondon, J. J., Quismorio, F. P., and Friou, G. J.. Ann. Intern. Med. 76, 65, 1972. Sher, J. H., and Pertschuk. L. P., J. Pediat. 85, 385, 1974. Gershwin, M. E.. Hyman, L. R., and Steinberg, A. D.. J. Pediat. 87, 588, 1975. Lampert, P. W., and Oldstone, M. B. A., Scicnw. 180, 408, 1973. Morgan, K. T., Gardiner, A. C., and Angus. K. W., .I. Conzp. Purhol. 87, 15, 1977. Koss, M. N., Chernack, W. J.. Griswold, W. R., and McIntosh, R. M., Arch. Pathol. 96, 331. 1973.

10. Peress, N. S., Miller, F., and Palu. W., J. Ncuropathol. Exp. Nrrrrol. 36, 561, 1977. 11. Peress, N. S., Miller, F., and Pam, W., J. Nrrrropathol. Exp. Nrurol. 36, 726. 1977. 12. Hoffman, S. A., Shucard, D. W.. Harbeck, R. J., and Hoffman, A. A.. .1. Nwwputhol. Nelrrol.

Erp.

37, 426, 1978.

13. Lampert, P., Garrett, R., and Lampert, A., Actu Ncrtroparhol. 38, 83, 1977. 14. McIntosh, R. M., Copack, P., Chernack, W. B., Griswold. W. R., Weil, R., and Koss, M. N., Arch.

Pathol.

99, 48, 1975.

15. McIntosh, R. M., Koss, M. N., Chernack, W. B., Griswold, W. R.. Copack, P. B., and Weil, R., Proc.

Sm.

Exp.

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Med.

147, 216, 1974.

16. Oldstone, M. B. A.. and Lampert, P. W.. Adrun. Biosci. 12, 381, 1974. 17. Lainson, R., Garnham, P. C. C., Kilhck-Kendrick, R.. and Bird, R. G., Brit. Med. ./. 2.470, 1964. 18. Tourtellotte, W. W., Tavolato, B., Packer. J. A., and Coimiso. P., Amh. Ncrtrol. 25, 345, 1971.

CSF DURING

ACUTE

IMMUNE

COMPLEX

DISEASE

425

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