Philip Y. Paterson

Neuroimmunologic Diseases: Effector Cell Responses and Immunoregulatory Mechanisms

CFA CNS EAE HAE-STA GPMBP GPK GPSC IFA Ig K cells LNC MBP MBP-SFs MS RIA(s) RK RMBP RSC T cells antigen binding capacity acute disseminated encephalomyelitis anti-thymocyte serum bone marrow derived or Bursa of Fabricius-equivalent immunoglobulin-sur face bearing lymphocytes complete Freunds adjuvant central nervous system experimental altergic encephalomyeiitis experimental altergic encephalomyetitis-supernate transfer activity guinea pig myelin basic protein guinea pig kidney guinea pig spinal cord incomplete Freunds adjuvant immunoglobulin non-T and non-B cells with high density of surface Fc receptors lymph node cells myelin basic protein myelin basic protein-serum factors multiple sclerosis radioimmunoassay(s) rat kidney rat myelin basic protein rat spinal cord thymus-derived or influenced lymphocytes

Intact B-cell activity is essential for complete expression of experimental allergic encephalomyelitis in Lewis rats.

Abstract B-Cell activity in weanling Lewis rats was inhibited by injections of goat anti-rat mu-chain antiserum (GAMS) from birth on, as demonstrated by markedly reduced or absent myelin basic protein (MBP) binding activity of sera. Following challenge with guinea pig spinal cord (GPSC)-complete Freunds adjuvant (CFA) and continued GAMS treatment, all rats remained clinically well without a trace of neurological signs. Histopathologically, central nervous system (CNS) perivascular fibrin deposits, typically accompanying paralytic signs of the disease, were virtually absent in GAMS-treated rats, despite occurrence of perivascular cell infiltrates of variable degrees of severity. In addition, preliminary studies of plastic embedded tissues suggest that demyelination is appreciably reduced in GAMS-treated and challenged rats. In contrast, control littermates similarly treated with normal goat serum (NGS) or normal goat IgG (NGIgG) and challenged, developed typical paralytic signs and perivascular fibrin deposits characteristic focal perivascular cellular infiltrates and demyelination of EAE, as well as anti-MBP antibodies.

Cyclophosphamide: Effect on Experimental Allergic Encephalomyelitis in Lewis Rats

Lewis rats sensitized to spinal cord in adjuvant and exhibiting advanced clinical paralytic signs of experimental allergic encephalomyelitis were treated with cyclophosphamide (5 milligrams per kilogram) daily. Of 30 treated animals, 21 recovered rapidly and appeared clinically well within 7 to 12 days. This immunosuppressive agent may prove therapeutically useful in the treatment of autoimmune diseases.

MULTIPLE SCLEROSIS : AN IMMUNOLOGIC REASSESSMENT*?

THE PURSUIT of the etiology of multiple sclerosis (MS) has accelerated in recent years, nourished by new evidence implicating immunologic factors in pathogenesis of the disease. The trail is not yet ‘hot’, but obviously getting warmer. In any ‘chase’ it’s a good idea to pause and take stock of the situation. In this editorial, the widely accepted thesis that MS is an immunologic disease is briefly examined. Concordant evidence is summarized. Special attention will be paid to discordant evidence, since this is where clues may be found for incisive future studies of this elusive disease.

Endogenous myelin basic protein-serum factors (MBP-SFs) and anti-MBP antibodies in humans: Occurrence in sera of clinically well subjects and patients with multiple sclerosis

Sera of normal subjects and patients wtih multiple sclerosis (MS) have been frequently found to contain picomolar quantities of endogenous myelin basic protein-serum factors (MBP-SFs). These serum factors, collectively representing a heterogeneous spectrum, were detected and measured by means of a competitive inhibition radioimmunoassay (RIA) designed to distinguish their respective binding affinities with anti-MBP reagent antiserum. Anti-MBP antibodies in these same normal and patient sera were also detected and their differing binding affinities determined. In general, when sera of normal subjects were found to contain free MBP-SFs, the reagent anti-MBP antibodies in the reagent antiserum used to detect them were of relatively high binding affinity (8 X 10(8) M-1). When normal sera were found to contain free anti-MBP antibodies, the affinities of such antibodies were invariably lower (0.06-0.7 X 10(8) M-1). In contrast, sera of patients with active MS and exhibiting clinical fluctuations in their disease, infrequently contained high or medium high affinity MBP-SFs, whereas higher affinity anti-MBP antibodies were commonly detected. These patterns of MBP-SFs and anti-MBP antibodies in normal and MS human sera resemble those previously observed in studies of normal Lewis rats and rats developing experimental allergic encephalomyelitis (EAE). The findings here reported provide additional support for the view that circulating endogenous MBP-SFs may function as neuroautotolerogens that restrict expansion of MBP-reactive lymphoid cell clones having potentially injurious effector activity for central nervous system (CNS) tissue.

Cellular transfer of experimental allergic encephalomyelitis: altered disease pattern in irradiated recipient lewis rats.

Abstract Irradiation of recipient Lewis rats 6–24 hr prior to injection of sensitized lymph node cells (LNC) altered the pattern of transferred experimental allergic encephalomyelitis (EAE). Recipients subjected to total body irradiation in doses ranging from 500 to 1000 rads developed paralysis; nonirradiated control recipients did not do so. Histopathologic changes of EAE, in terms of number of descrete cellular infiltrates, were potentiated in the total body irradiated recipients. Among LNC recipients subjected to regional irradiation (850 rads) of the head or lower spinal column, paralysis was observed only in those animals where the irradiation impinged upon the spinal cord. Cellular infiltrates of EAE were numerically more common in the irradiated region of the neuraxis. The findings are discussed in terms of irradiation rendering the central nervous system of animals and man more vulnerable to autoimmune injury.

Neurovascular permeability and fibrin deposition in the central neuraxis of Lewis rats with cell-transferred experimental allergic encephalomyelitis in relationship to clinical and histopathological features of the disease

Abrupt increases in blood-brain barrier (BBB) permeability were detected by the dual-isotope technique, coinciding with evidence of activation of coagulation cascade, occurred 1 day prior to appearance of clinical neurological signs of experimental allergic encephalomyelitis (EAE) and in conjunction with initial detectable cell infiltration. Maximal increase of BBB permeability was observed on the first day of clinical signs, which was 2 days prior to maximum severity of clinical abnormalities and 1 day in advance of the greatest number of central nervous system (CNS) fibrin deposits and perivascular cellular infiltration. Returning of increased BBB permeability and CNS perivascular fibrin deposits to normal levels was demonstrated prior to complete remission of neurological signs. Considerable CNS perivascular cellular infiltrates, however, lasted after complete remission of neurological signs. These findings indicate that increased permeability of the BBB, in association with activation of the coagulation cascade, is the earliest expressions of immune effector activity of experimental allergic EAE.

Magnetic protein A microspheres: A rapid method for cell separation

Abstract Magnetic albumin microspheres (1 μm average diameter) containing Staphylococcal protein A have been synthesized and used as solid carriers for IgG. Because protein A is known to specifically bind the Fc portion of IgG, antisera can be coupled to the microspheres after very brief incubation at 37°C without the use of chemical coupling agents. Either rabbit anti-chicken RBC or rabbit anti-rat Ig was coupled to microspheres. Subsequent incubation of the IgG-bearing microspheres with heterogeneous cell populations resulted in the magnetic removal of 97.8% of the chicken RBCs and 99.5% of the Ig-bearing splenocytes. This method represents a more rapid and efficient method for cell fractionation than has previously been described.

Antigen-specific inhibition of the adoptive transfer of experimental autoimmune enceophalomyelitis in Lewis rats

The efficacy of antigen-specific immunoregulation as a treatment for the efferent limb of an autoimmune disease was tested in a rat model of adoptive experimental autoimmune encephalomyelitis (EAE). Lewis rats receiving 4-5 x 10(7) guinea pig (GP) myelin basic protein (MBP)-activated lymph node T cell blasts from GPMBP/CFA sensitized donors routinely show clinical signs of disease 5-6 days post transfer. Intravenous injection of GPMBP coupled to syngeneic splenocytes using the chemical cross-linker carbodiimide was effective in completely abrogating the expression of clinical EAE in rats that received MBP-specific T cells 2 days previously. Partial inhibition was also observed in rats injected as early as day 0 (the same day as MBP-specific T cell transfer) and as late as 1 day prior to the onset of clinical signs (days 4-5 post transfer). Unresponsiveness was shown to be dose-dependent, dependent on the route of injection of the neuroantigen-coupled splenocytes, and was antigen-specific. Splenocytes coupled with GP or rat MBP (which are identical within the major encephalitogenic GP68-86 Lewis rat determinant with the exception of the residue at position 80) were equally efficient at eliminating disease expression in recipients of GPMBP-specific T cells. In contrast, splenocytes coupled with bovine or rabbit MBP (which differ significantly from GPMBP within the 68-86 region) had no inhibitory effect. The antigen specificity of the tolerance induction was also illustrated by the fact that splenocytes coupled with GP68-86, but not those coupled with the truncated GP68-84 peptide, induced profound unresponsiveness. Interestingly, de novo antigen processing by the antigen-coupled cells did not appear to be necessary as the inclusion of antigen processing inhibitors had no effect on inhibition of disease. However, the use of the carbodiimide coupling reagent was critical for the induction of unresponsiveness as essentially equivalent amounts of 125I-labelled MBP were bound in its presence or absence, but only splenocytes incubated in the presence of both MBP and carbodiimide inhibited clinical expression of disease. Antigen-specific tolerance is thus an effective means of inhibiting expression of clinical disease in the rat EAE model, and a powerful tool for determining the fine epitope specificity of encephalitogenic T cells.

Serum degradation of myelin basic protein with loss of encephalitogenic activity: Evidence for an enzymatic process☆

Abstract Fibrin deposition in parallel with loss of myelin basic protein (MBP), an antigenic constituent of central nervous system (CNS) myelin, within the lesions of animals with experimental allergic encephalomyelitis (EAE) suggested that degradation of MBP by proteolytic activity associated with blood clotting might be an important immunopathologic event in this prototypic autoimmune disease. Following incubation in normal rat serum at 37 °C for more than 4 hr, but not to any comparable degree in plasma, MBP had little or no encephalitogenic activity when bioassayed in guinea pigs or rats. Fragments of increasingly lower molecular weight were demonstrable by polyacrylamide gel electrophoresis after addition of MBP to rat serum; no fragments appeared after incubating the protein in rat plasma. Little or no loss of encephalitogenic activity was observed when MBP was incubated in serum containing protease inhibitors. These findings indicate that the serum-mediated degradation of MBP and concomitant loss of encephalitogenic activity is due to an enzymatic process associated with the coagulation cascade or/and the complement, kallikrein or fibrinolytic pathways. Implications of these findings concerning EAE and the multiple sclerosis process in man are discussed.