Experimental allergic encephalitis. Dissociation of cellular immunity to brain protein and disease production

Molecular mimicry revisited: gut bacteria and multiple sclerosis

Molecular mimicry is a possible explanation for autoimmune side effects of microorganism infections. Protein sequences from a particular microorganism are compared to known autoimmune immunogens. For diseases such as multiple sclerosis (MS), where the infectious agent is unknown, guesses to its identity are made. Mimics are assumed to be rare. This study takes a radically different approach. Reported sequences from all known human bacterial and viral agents were searched for autoimmune immunogen mimics. Three encephalitogenic peptides, whose autoimmune requirements have been studied extensively, were selected for comparison. Mimics were seen in a wide variety of organisms. For each immunogen, the mimics were found predominantly in nonpathogenic gut bacteria. Since the three immunogens used in this study are related to MS, it is suggested that a microorganism responsible for autoimmune activity in MS could be a normally occurring gut bacterium. This would explain many of the peculiar MS epidemiological data and why no infective agent has been identified for MS and supports recently found MS gut metabolism abnormalities.

Central nervous system myelin: structure, function, and pathology

Multiple sclerosis (MS) and a number of related distinctive diseases are characterized by the active degradation of central nervous system (CNS) myelin, an axonal sheath comprised essentially of proteins and lipids. These demyelinating diseases appear to arise from complex interactions of genetic, immunological, infective, and biochemical mechanisms. While circumstances of MS etiology remain hypothetical, one persistent theme involves recognition by the immune system of myelin-specific antigens derived from myelin basic protein (MBP), the most abundant extrinsic myelin membrane protein, and/or another equally susceptible myelin protein or lipid component. Knowledge of the biochemical and physical-chemical properties of myelin proteins and lipids, particularly their composition, organization, structure, and accessibility with respect to the compacted myelin multilayers, thus becomes central to the understanding of how and why these antigens become selected during the development of MS. This review focuses on current understanding of the molecular basis underlying demyelinating disease as it may relate to the impact of the various protein and lipid components on myelin morphology; the precise molecular architecture of this membrane as dictated by protein-lipid and lipid-lipid interactions; and the relationship, if any, between the protein/lipid components and the destruction of myelin in pathological situations.

Serotonin binding sites. II. Muramyl dipeptide binds to serotonin binding sites on myelin basic protein, LHRH, and MSH-ACTH 4-10

Previously, we reported the existence of structurally similar serotonin binding sites on myelin basic protein, LHRH, and MSH-ACTH 4-10. We now report that the adjuvant peptide, muramyl dipeptide (N-acetyl-muramyl-L-Ala-D-isoGln) also binds to these sites. This observation may help to explain previous observations of serotonin-like activity by muramyl peptides, including the promotion of slow-wave sleep and fever induction. The observation may also provide an important link between the immune system and the nervous system that may explain the role of muramyl dipeptide adjuvants in causing autoimmune diseases to serotonin-regulated proteins and their receptors, as well as the alterations in serotonin levels that are often observed in autoimmune diseases. The observation provides concrete evidence for a dual-antigen hypothesis for the induction of autoimmune diseases by an adjuvant-peptide complex. Application of such a mechanism for induction of autoimmunity may be of importance in understanding a number of postinfectious and postvaccinal neuropathies, and suggests a possible etiology for autism, in which many patients have high blood serotonin levels, autoimmune reactions to myelin basic protein, and antibodies to serotonin binding sites. Finally, the observation suggests that glycopeptides may act as neurotransmitters.

Immunologic differences in murine glial cells and their association with susceptibility to experimental allergic encephalomyelitis

We tested the hypothesis that glial cells from mice resistant or susceptible to the autoimmune disease experimental allergic encephalomyelitis (EAE) may differ in their abilities either to express Ia antigens and/or stimulate anti-class II (Ia)-specific T-cells. Ia antigens were induced on glial cells from EAE-susceptible (SJL/J) and -resistant (B10.S and DBA/2) strains of mice by culture with lymphokines from activated T-cells (2 degrees SN). Ia antigen expression was quantified with an enzyme-linked immunosorbent assay (ELISA) in which glia were exposed to monoclonal anti-Ia antibodies and alkaline phosphatase-labeled anti-mouse Ig antibodies. The ability of glial cells to stimulate anti-Ia T-cells was quantified by culturing irradiated glial cells with anti-Ia-specific T-cell lines and measuring the amounts of [3H]thymidine incorporated by these lines. Glial cells from all strains of mice could be induced to express Ia antigens and upon exposure to high concentrations of lymphokines, amounts of expressed Ia antigen were equivalent. However, at limiting lymphokine concentrations, glia from the EAE-resistant strain B10.S expressed greater amounts of Ia antigen than did glia from SJL/J mice (p less than 0.05), suggesting that B10.S glia were more sensitive to the Ia-inducing effects of T cell lymphokines. In contrast to the above results, glia from EAE-susceptible SJL mice consistently demonstrated an increased ability to induce T-cell proliferation in lines specific for Ias antigen, compared to glia from EAE-resistant mice, even those of the same Ia haplotype (i.e. B10.S). Spleen cells from resistant strains had equivalent and frequently greater ability to induce anti-Ia-specific T-cell proliferation than did SJL spleen cells. These data suggest (a) that there are differences in the sensitivity of glia from different strains of mice to the Ia antigen-inducing effects of T-cell lymphokines, (b) that expression of Ia antigen does not necessarily correlate with the ability to stimulate Ia-specific T-cells, (c) that there are organ-specific differences in the ability to stimulate Ia antigen-specific T-cells, and (d) that an additional variable involved in determining resistance or susceptibility to an organ-specific autoimmune disease may be the ability of the target organ to stimulate anti-Ia-specific T-cells.

Chronic-relapsing experimental allergic encephalomyelitis in strain-13 guinea pigs: cell-mediated immunity and IgG isoelectric focusing in myelin basic protein-liposome-treated and untreated animals

Juvenile strain-13 guinea pigs challenged with whole central nervous system (CNS) tissue in complete Freund's adjuvant (CFA) developed chronic-relapsing (CR) experimental allergic encephalomyelitis (EAE). The animals that recovered from the first clinical episode were divided into three groups. One group was left untreated, one group was treated with three intracardiac injections of 100 micrograms glutaraldehyde-fixed myelin basic protein (MBP)-liposomes (MBP-L-GA) given once a week, and one group was treated with cytochrome c-liposomes (CYC-L-GA). The animals treated with MBP-liposomes were very well protected against further relapses. In vitro proliferative responses of peripheral blood lymphocytes (PBL) were performed repeatedly on most animals. The lymphocytes exhibited excellent proliferative responses to MBP, proteolipid apoprotein (PLP) and whole myelin, as well as to purified protein derivative (PPD) and concanavalin-A (ConA). High proliferative responses were recorded over the entire period of observation which lasted 12-22 months, each time the animals were tested in remission or in full relapse. However, a sharp decrease in proliferative responses was observed in most animals when the assay was performed 24-48 h before to 24 h after entering a relapse. The results demonstrate the presence of long-term and sustained cell-mediated responses to two distinct neuroantigens, and show fluctuations of both neuroantigen-specific and nonspecific responses concordant with a well-defined phase of the disease. Isoelectric focusing and immunofixation was performed on sera and cerebrospinal fluids obtained at the time of sacrifice. The pattern showed clear oligoclonal IgG bands (OB) in the samples obtained from untreated, CYC-L-GA-treated as well as in the MBP-L-GA-treated animals.

Clinical suppression of experimental allergic encephalomyelitis by muramyl dipeptide "adjuvant"

Experimental allergic encephalomyelitis (EAE) is a model for several human diseases including multiple sclerosis and post-vaccinal encephalopathies. EAE is generally thought to be an autoimmune response to the antigen myelin basic protein (MBP). Oddly, MBP can also suppress EAE, and many observations suggest that an independent immune response to so-called "adjuvant" material is also necessary to EAE induction. Thus, EAE may be a result of a pair of interactive immune responses, one against MBP, and one against adjuvant. If so, the adjuvant should, like MBP, suppress EAE. We present data from experiments on strain 13 guinea pigs demonstrating EAE suppression by muramyl dipeptide, an active component of complete Freund's adjuvant. These results are striking because classically adjuvants are defined as immunopotentiators, not immunosuppressants. Our results, therefore, suggest that a revaluation of the role of adjuvants in inducing autoimmune diseases may be necessary.

Evolutionary divergence in the structure of myelin basic protein: comparison of chondrichthye basic proteins with those from higher vertebrates

A basic protein has been purified from the CNS myelin of the gummy shark (Mustelus antarticus). Electroblotting was used to examine the capacity of rabbit antisera raised against this electrophoretically pure protein to recognize myelin basic protein from higher vertebrates. The antisera bound to two shark proteins including the original polypeptide antigen and to chicken, bovine, and human myelin basic proteins. Thus, the shark protein appeared to possess antigenic determinants that have been retained through evolutionary divergence of these proteins. Whereas bovine basic protein caused experimental allergic encephalomyelitis in guinea pigs, animals that received injections of the shark protein showed neither clinical nor histological signs of this disease. However, tests for delayed-type hypersensitivity and for Arthus reaction following injection with the shark protein revealed a T-cell-mediated response to this antigen and substantial cross-reactivity with higher vertebrate basic proteins. Analysis of the amino acid composition of the shark protein, and comparison of its tryptic peptide map with that of the bovine protein, revealed substantial changes in the amino acid sequence. Although the shark protein has some antigenic determinants in common with the proteins from higher vertebrates, it appears that much of the structure differs.

Experimental allergic encephalomyelitis: clinical disease and enhanced cellular transfer in the absence of lymphocyte proliferative responses against syngeneic MBP

Experimental allergic encephalomyelitis (EAE) was induced in Lewis rats using several different immunization protocols, and draining lymph node cells from these animals were assayed for proliferation against heterologous, homologous, and syngeneic MBP, and syngeneic spinal cord. Proliferative responses were largely stimulated by nonsyngeneic antigenic determinants and correlated better with the antigen used to induce EAE than with signs of autoimmune disease. Lymph node cells from rats immunized with either guinea pig spinal cord or syngeneic MBP did not proliferate measurably when restimulated in vitro with syngeneic MBP, yet lymphoid cells from these animals were enhanced in their capacity to transfer EAE following in vitro stimulation with syngeneic MBP.

Induction of experimental allergic encephalomyelitis in Lewis rats with purified synthetic peptides: delineation of antigenic determinants for encephalitogenicity, in vitro activation of cellular transfer, and proliferation of lymphocytes

Four highly purified synthetic peptides encompassing segments of the 68-86 region [for the numbering system used, see Eylar, E.H., Brostoff, S., Hashim, G., Caccam, J. & Burnett, P. (1971) J. Biol. Chem. 246, 5770-5784] of myelin basic protein (MBP), a region known to induce experimental allergic encephalomyelitis (EAE) in Lewis rats, were used to define and compare structure-function relationships between the primary structure of the 68-86 sequence and the three following biological activities: induction of EAE in Lewis rats, stimulation of T lymphocytes in vitro as measured by augmented cellular transfer of EAE to syngeneic recipients, and lymphocyte proliferation, as measured by [3]thymidine incorporation. Guinea pig (GP) MBP was approximately 60 or 1500 times more active than the GP68-84 (Y G S L P Q K S Q R S Q D E N; single-letter amino acid abbreviations) or the modified bovine (MB) 68-84 (Y G S L P Q K A Q R P Q D E N) peptides for induction of EAE, respectively. Furthermore, lymphocytes primed with either GPMBP, GP68-84, or MB68-84 crossreacted in vitro with either GPMBP, GP68-84, or MB68-84 for activation of lymphocyte transfer activity. In contrast, lymphocytes primed with either GP68-84 or MB68-84 exhibited antigen-specific proliferation in vitro exclusively in response to either GP or MB sequences, respectively. Neither GP75-84 (S Q R S Q D E N) nor GP75-86 (S Q R S Q D E N P V) induced EAE, activated lymphocytes for EAE transfer, or stimulated lymphocyte proliferation under conditions and doses tested. We conclude that (i) structurally distinct determinants, reflecting existence of functionally independent classes of antigen receptors, specify encephalitogenic and proliferative responses of primed lymphocytes and (ii) determinants for EAE induction, cellular transfer of EAE, and lymphocyte proliferation include amino acid residues in the 68-74 (Y G S L P Q K) sequence of GPMBP.

The role of myelin lipids in experimental allergic encephalomyelitis. Part 1. Influence on disease production by non-encephalitogenic doses of myelin basic protein

Hartley guinea pig central nervous system (CNS) myelin has been purified and fractionated into its protein and lipid components. Experimental allergic encephalomyelitis (EAE) was induced in juvenile strain 13 guinea pigs with both lyophilized and fresh 'wet' myelin. However, a larger dose of lyophilized myelin was required to induce chronic EAE. Total myelin lipids, galactocerebrosides, gangliosides, phospholipids or proteolipids were combined with a non-encephalitogenic dose of myelin basic protein (MBP) and injected in juvenile Hartley guinea pigs. No clinical or histological manifestations of disease were observed. Parameters of immune functions indicated that the total myelin lipids augmented cell-mediated immune responses as measured by in vitro lymphocyte transformation and by a significant decrease in the percentage of peripheral early T cells. Only the proteolipids elicited delayed hypersensitivity reactions. Animals that received the phospholipid-MBP combination showed no changes when compared to animals injected with MBP alone. The results suggest that although the myelin lipids did not act synergistically with a non-encephalitogenic dose of MBP to induce EAE, they induced immunological changes and potentiated the immune response to MBP.

Delayed-type hypersensitivity to myelin basic proteins in mice susceptible to allergic encephalomyelitis

The delayed-type hypersensitivity (DTH) response in mice immunized with autologous spinal cord homogenate or purified myelin basic protein (MBP) was measured by the 125I-UdR uptake ear assay. Mice were tested for DTH responses with MBP preparations from different species and with synthetic peptides. The 114-122 and 68-84 peptide regions appear to be major determinants for inducing and eliciting DTH in the mice which are susceptible to allergic encephalomyelitis.

Suppression of experimental allergic encephalomyelitis in Lewis rats treated with myelin basic protein-liposome complexes: clinical, histopathological, and cell-mediated immunity correlates

Guinea pig myelin basic protein (MBP) was inserted into phosphatidylserine liposomes and Lewis rats were injected by the intracardiac (ic) route with 75 microgram doses of MBP-liposomes according to various schedules. After challenge with 75 microgram guinea pig MBP in complete Freund's adjuvant, the rats were followed for clinical signs, were tested for delayed hypersensitivity (DTH) and lymphocyte transformation (LT) to MBP. The animals were sacrificed 30 days after challenge and the central nervous system tissue was examined for histological modifications. Rats treated with two injections of MBP-liposomes, 7 days before and 7 days after challenge, showed the highest degree of protection from clinical manifestations. Histological lesions were not significantly reduced. DTH reactions to MBP were all positive, regardless of treatment. LT assays were positive overall in only 50% of the animals tested. The response to rat MBP was significantly lower than to guinea pig MBP, especially in the groups treated with MBP-liposomes. Adoptive transfer of spleen cells from MBP-liposome-treated donors reduced the clinical scores of actively induced EAE in syngeneic recipients by 40-50%. These results suggest that at least one mechanism responsible for antigen-specific protection in EAE by MBP-liposomes operates through active suppression transferable by spleen cells.

Influence of cerebroside and ganglioside on the encephalitogenic activity of myelin basic protein in guinea pigs

The effect of 2 central nervous system glycolipids (cerebroside and ganglioside) on the encephalitogenic activity of bovine myelin basic protein (MBP) was studied in guinea pigs. Mixing each of these glycolipids with MBP and injection of these mixtures in Freund's incomplete adjuvant (FIA) abrogated the resistance to encephalomyelitis upon challenge with MBP in Freund's complete adjuvant (FCA). Primary injection of these glycolipid-MBP mixtures in FCA diminished the clinical signs of experimental allergic encephalomyelitis (EAE) as compared to primary injection of MBP in FCA. Considering the amount of ganglioside needed to optimally induce these effects, this phenomenon seemed to be aspecific. However, with cerebroside, only minor quantities were sufficient, suggesting specific interaction with the basic protein. In several aspects, close correlation was found between cellular immune activity to MBP as measured by skin reactivity and the development of EAE.

An explanation of prevention and suppression of experimental allergic encephalomyelitis

An explanation of experimental allergic encephalomyelitis prevention and suppression is presented based upon evidence that the active unit in disease induction is an encephalitogen-adjuvant complex. The stereochemical complementarity in structure of the encephalitogen and adjuvant is mirrored in complementarity in the recognition sites of lymphocyte populations activated against encephalitogen and adjuvant. Since two complementary lymphocyte populations are necessary for disease induction, any procedure that prevents the development of one of these populations will prevent disease induction. Any procedure that eliminates one population after induction has occurred will suppress the disease. We argue that all extant data support the hypothesis. Several new experiments are proposed to further test it.

Suppression and treatment of experimental allergic encephalitis in guinea-pigs with the bovine spinal cord protein (BSCP)

Experimental allergic encephalitis (EAE) was suppressed in guinea-pigs that had been sensitized with 50 micrograms of bovine myelin basic protein (MyBP) in Freund's complete adjuvant (FCA) by daily injections of 500 micrograms of the bovine spinal cord protein (BSCP) in saline between day 8 (D 8) and D 23 after sensitization. Injections of 500 micrograms of bovine serum albumin in saline, or saline alone, did not suppress disease. Reversal of clinical disease was achieved with doses of 750 micrograms of BSCP in saline when treatment was begun within a day after the first sign of disease was observed. Six injections of 500 micrograms of BSCP in Freund's incomplete adjuvant (FIA) were required to suppress EAE whether BSCP-FIA injections were begun on D 0 or as late as D 8 when T cells sensitized to MyBP had invaded the central nervous system. When administration of BSCP-FIA was withheld until after disease onset, only three or four injections were needed to reverse clinical signs. BSCP appeared to be as effective quantitatively as MyBP in the suppression or treatment of disease. Because there is no cross-reaction between BSCP and MyBP at the antibody level, the present results raise the possibility that the suppressive activity of BSCP may be due to an amino acid sequence in BSCP and MyBP that is recognized only by T cells. When antigens were injected in FIA at 4 day intervals after sensitization, the onset of disease was delayed up to 5 days. Moreover, even bovine gamma-globulin appeared to have suppressive activity when injected three or four times in FIA. The findings suggest that assessments of the suppressive capacity of an antigen may be inaccurate if the antigen is injected in FIA frequently during the interval between sensitization and onset of disease.

Suppression and reversal of allergic encephalomyelitis in rhesus monkeys with basic protein and peptides

We have extended earlier studies on the suppression of clinically evident experimental allergic encephalomyelitis (EAE) in monkeys, repeated injections of human basis protein. The results confirm that after suppressive treatment, recovered animals remain clinically normal and do not show spontaneous recurrence of symptoms. However, recovered animals are susceptible to EAE upon renewed challenge, and they develop the disease more rapidly and more severely than after the initial challenge; resuppression is also accomplished in these cases by the same methods used previously. The results indicate further that the basic protein or peptide T administered without mycobacteria is effective in suppressing the development of basic protein-induced EAE regardless of the species from which it was derived.

Cell-mediated immunity to myelin basic protein in Lewis rats made unresponsive to experimental allergic encephalomyelitis

Lewis rats with experimental allergic encephalomyelitis (EAE) exhibited cell-mediated immunity to myelin basic protein as determined both with in vivo and in vitro assays. Positive skin test reactions and production of migration inhibitory factor (MIF) were observed before onset and after recovery from EAE. Rats rendered unresponsive to EAE exhibited in vitro cell-mediated immunity to basic protein, although in vivo manifestations were depressed. However, tolerant rats failed to respond to the encephalitogenic determinant; rats with EAE exhibited cell-mediated immunity to this region of the molecule. The results indicate that EAE-unresponsive rats possess lymphocytes capable of responding to basic protein, but that reactivity to the encephalitogenic peptide is suppressed.

Myelin basic protein serum factor. An endogenous neuroantigen influencing development of experimental allergic encephalomyelitis in Lewis rats

Age-related concentrations of myelin basic protein serum factor (MBP-SF), an endogenous neuroantigen detected and quantitated by inhibition of binding of rat myelin basic protein (RMBP) antibody with 125I-RMBP reagent antigen and immunochemically indistinguishable from native RMBP in this respect, reach peak levels as high as 21 ng/microliter among 2-3-wk-old normal suckling Lewis rats. Levels then progressively decline to low, usually undetectable levels of less than or equal to 0.6 ng/microliter MBP-equivalents in adult animals by 7 wk of age. MBP-SF levels are inversely related to the age-related increasing capacity of maturing Lewis rats to develop experimental allergic encephalomyelitis (EAE) after sensitization to MBP of syngeneic, but not xenogeneic, origin. MBP-SF appears to be an endogenous neuroimmunoregulatory product of potential importance for immunologic tolerance to autologous RMBP in Lewis rats.

Experimental allergic encephalitis: study of cellular immunity during disease suppression

Administration in complete Freund's adjuvant of encephalitogenic protein (EP), derived from central nervous tissue to guinea pigs, regularly results in the development of experimental allergic encephalitis (EAE) which leads to the death of the animals. Administration of EP in incomplete Freund's adjuvant at an appropriate time will completely suppress the clinical development of disease. Results reported herein show that animals receiving suppressive injections of EP for 7 days show depression of lymphocyte DNA synthesis and macrophage migration inhibition, but not of skin reactivity, in response to EP immediately following the injections, and subsequently show recovery of lymphocyte reactivity but do not develop clinical manifestations of EAE. Humoral or other factors may prevent the development of disease in these animals. Guinea pigs receiving injections of EP for 14 days show profound and prolonged depression of lymphocyte reactivity to EP and macrophage migration inhibition. Possible mechanisms for these results include a diminished number or function of reactive cells or activity of a population of cells with the capacity to suppress cellular immune responses. Nonspecific suppression of reactivity to an unrelated antigen during the suppressive injections was not observed.

Peptides and autoimmune disease

The use of derived and synthetic peptides has contributed greatly to our understanding of encephalitogenic determinants in the basic protein molecule. Peptides derived from BP by use of trypsin, pepsin, cathepsin D (brain and liver) and BNPS-skatole have proven most useful. Synthetic peptides have served to define the disease-inducing determinants with precision. A remarkable feature of these studies is that different antigenic determinants serve as encephalitogenic sites in different species. The encephalitogenic sites comprise short peptide domains of the BP polypeptide chain, only 8 residues (rat), 9 residues (guinea pig), and 10 residues (rabbit) in length. In view of the requirement for both haptenic and carrier specificity of an immunogenic molecule, it is impressive that these peptides themselves elicit the autoimmune disease, EAE. While less active than BP on a molar basis, they are nonetheless potent encephalitogens, producing clinical signs in rats and guinea pigs at less than 1 microgram dose. The data indicate that for most animal species (guinea pig, rat, monkey) there appears to be only one major encephalitogenic determinant, an unusual finding in view of the number of antigenic determinants for cell-mediated immunity existing in the BP molecule. Possibly a combination of genetic and anatomical factors may account for this phenomenon. A relationship may exist between multiple sclerosis and EAE as shown by peptide studies; lymphocytes are found in MS patients during exacerbation sensitized to the same region of BP active in the monkey. The major encephalitogenic sites are: Guinea Pig (9) Phe-Ser-Trp-Gly-Ala-Glu-Gly-Gln-Lys(Arg); Rabbit (10) Thr-Thr-His-Tyr-Gly-Ser-Leu-Pro-Gln-Lys; Rat (8) Ser-Gln-Arg-Ser-Gln-Asp-Glu-Asn; Monkey (14) Phe-Lys-Leu-Gly-Gly-Arg-Asp-Ser-Arg-Ser-Gly-Ser-Pro-Hser.

Immune response of Lewis rats to peptide C1 (residues 68-88) of guinea pig and rat myelin basic proteins

Peptide C1 (residues 68-88) from GP and rat BP differ by a single amino acid interchange at residue 79. This residue is serine in GP C1 and threonine in rat C1. GP C1 was encephalitogenic in Le rats at doses as low as 15 ng. Rat C1 was encephalitogenic at doses of 1,500 ng or greater. LNC from rats challenged with 25 X 10(-4) micronmol of GP C1 and 250 X 10(-4) micronmol of rat C1 showed a proliferative response in vitro to both peptides, but in each instance the magnitude of the response was greater to the GP peptide. GP C1 also induced higher levels of circulating antibodies at 25 X 10(-4) micronmol, but the specificity of antibodies produced by the two peptides was the same. These results have been interpreted as indicating that the presence of serine at position 79 in GP C1 results in the stimulation of greater numbers of T cells involved in (a) the induction of EAE, (b) the in vitro proliferative response and (c) helper function in antibody production.

Molecular internalization of a region of myelin basic protein

The conformation of myelin encephalitogenic or basic protein (BP) was investigated with a double-antibody radioimmunoassay by studying the reaction of BP or its fragments with antibodies produced in two rabbits against peptide 43-88 linked to rabbit serum albumin. Both antisera reacted well with peptide 43-88 but showed little or no reaction with BP. Absorption of these antisera with a BP-immunoadsorbent did not remove the antibody activity against peptide 43-88. Within the region of peptide 43- 88 it was shown that peptides 68-88 and 79-88 gave an equivalent or better reaction than peptide 43-88, whereas peptides 43-67 and 64-73 had very little reactivity. In the BP fragments containing region 43-88, peptide 1-88 showed the best reactivity, peptide 20-166 showed minimal reactivity, while peptide 1-115 showed none. These data document the internal position of at least a portion of peptide 43-88 and all of residues 79-88 in the BP molecule. The much greater reactivity of peptide 1-88 as compared to peptide 1-115 suggests that the region or a portion of the region of BP containing residues 89- 115 participates in the conformational alignment of BP restricting access to peptide 79-88. After absorption with BP, neither of the antisera prepared to peptide 43-88 reacted with PNS myelin in fixed tissue sections but continued to react with CNS myelin in similarly treated sections. The present findings demonstrate the need to consider the role of shielded antigenic determinants in the investigation of antigens or of immune responses.

Cell-mediated immune response to guinea pig and bovine basic proteins of myelin in Lewis and PVG rats and their hybrids

The in vitro cell-mediated immune response of rat lymph node cells (LNC) to guinea pig and bovine encephalitogenic protein (EP) has been studied with a LNC transformation test. LNC were obtained from either Lewis, PVG, or F1 (Lewis x PVG) rats 28 days after challenge with guinea pig or bovine EP in Freund's complete adjuvant (FCA) of different mycobacterium content. No differences between the strains or their hybrids in LNC response could be shown if stimulated with sensitizing EP, despite the great differences in capacity for disease development in those animals. Nor did a fivefold lowering of the amount of mycobacterium content in FCA, when guinea pig EP was used at challenge, lessen the in vitro response, although this reduces the disease development. Sensitization with guinea pig EP causes an in vitro cross-reactivity to bovine EP and the reciprocal cross-reactivity probably also exists. In rabbits, this cross-reactivity in both directions was clear-cut. LNC from Lewis rats challenged with guinea pig EP in FAC, with the higher amount of mycobacterium, showed in vitro responses to tested peptides of this EP; the amino acid sequences of these were: 1-42, 43-88, 89-169, and HNB-89-169 (89-169 blocked at the tryptophan-residue by hydroxynitrobenzylation).

Multiple sclerosis: sensitization of a myelin basic protein fragment (peptide T) encephalitogenic to primates. A preliminary report

Myelin basic A1 protein is the sole antigen of the central nervous system capable of inducing experimental allergic encephalitis (EAE), but sensitization with peptide fragments of the molecule may also induce disease. Using the macrophage migration inhibition factor (MIF) assay we have compared sensitization to portions of the molecule active in inducing EAE in monkeys with results obtained concomitantly using the intact protein. Cellular sensitization to human myelin A1 protein, peptide L (residues 1-116), peptide T (residues 117-170), and petide Y (residues 154-170) was studied using the Thor-Rocklin MIF assay system. Lymphocytes of 10 normal subjects, 10 multiple sclerosis patients 0-3 weeks after onset, 10 4 weeks to 3 months after and 10 6 months or longer after onset of an acute exacerbation were assayed. Results of the investigation reveal evidence of cellular sensitization to myelin basic protein encephalitogenic peptide T occurring during attacks of multiple sclerosis. Peptide L, relatively nonencephalitogenic to primates, failed to induce a significant lymphocyte response, whereas peptide Y which is encephalitogenic gave irregular results.

Autoimmune disease antigens

The first step towards understanding the cellular interaction which results in autoimmune disease is to determine what triggers the recognition between a specific autoimmune antigen determinant and the cellular receptor. In this review, we have focused on the antigen inducing experimental allergic encephalitis (EAE) because the antigen has been characterized and a relatively large body of information on its biological activities has been accumulated. Clearly, a specific allergic encephalitis-producing determinant is present and is represented on a relatively small portion of the molecule. The determinant induces a wide variety of biological reactivities, some of which are classed as cellular mediated. An attempt is made to dissect activities such as blast transformation (BT), migration inhibitory factor (MIF), in vivo delayed type hypersensitivity reaction (DTH) and EAE and to relate them to the structural requirements which the determinants possess. The complexities which arise indicate that subpopulations of cells with different receptor activities may respond selectively and that recognition of the receptor is produced by an EAE determinant consisting of three amino acids in a specific linear sequence. Furthermore, under experimental circumstances the EAE activity can be dissociated from the other activities (BT, MIF, DTH), indicating that while these tests are used generally to follow various human autoimmune disease activities, they may represent the reaction of a broad spectrum of cells.

Autoimmune murine thyroiditis IX. Relationship of humoral and cellular immunity to thyroiditis in high and low responder mice

Good responder (C57/Br/cd) and poor responder (C57BL/10) mice were immunized with mouse thyroid extract in Freund's complete adjuvant. The good responder mice first showed antibody to thyroglobulin on the seventh day while the poor responder animals had slightly lower titers and antibody did not appear until day 12. The first signs of thyroid infiltration appeared on day 4 in the responder strain, and severe lesions were seen between the third and fifth week. In contrast, the poor responder mice showed almost no evidence of infiltration. The macrophage disappearance reaction, a measure of cell-mediated immunity, was similar in the responder and nonresponder strains.

Experimental autoimmune encephalomyelitis in mice: genetic control of susceptibility

Experimental autoimmune encephalomyelitis (EAE) was induced in inbred and congenic strains of mice by injection of mouse spinal cord homogenate (MSCH) in Freund's complete adjuvant (FCA) with pertussis vaccine. Genetic analyses showed that susceptibility to EAE in mice was inherited as a dominant trait and was in part controlled by genes located in the centromeric half of the H-2 complex. Mice with EAE developed cell-mediated immune responsiveness to basic protein of myelin (BPM), as judged by the macrophage migration inhibition assay, using peritonealyexudate cells; this was not observed with mice of resistant strains. However, the migration of peritoneal exudate cells of both susceptible and resistant strains was significantly inhibited in the presence of purified protein derivative (PPD) of M. tuberculosis. Thus, the genes involved in the control of susceptibility to EAE also influence T cell responsiveness to BPM. Antibody to BPM, as judged by radioimmunoassay, was detected in susceptible and resistant strains but there was no correlation between the presence or levels of antibody and susceptibility or resistance to EAE. It is suggested that resistance to EAE is associated with failure of T cells to recognize and/or respond to the encephalitogenic determinant of the BPM molecule.

Comparison of allergic aspermatogenesis with that induced by vasectomy. I. In vivo studies in the guinea-pig

Groups of male and female guinea-pigs were immunized with homologous epdidymal sperm in Freund's complete adjuvant (FCA) and skin tested at weekly intervals with a heat-treated extract of the sperm or with PPD. In females, the skin response to both antigens was similar to that to any standard protein antigen. In males, the response to sperm extract varied with the induced auto-immune orchitis, reaching a maximum immediately after testis lesion was most severe and as recovery was beginning (shown histologically): the response to PPD was decreased at 1 week after immunization, but subsequently was similar to that in females. Skin tests on guinea-pigs 8 months after bilateral vasectomy (when both ends of vasa were ligated), showed no evidence of delayed hypersensitivity to sperm, although there was marked histological evidence of reduced spermatognesis, due to back pressure atrophy.

Blocking the encephalitogenic activity of the C-terminal part of the basic myelin protein in rabbits by treatment with serum

Peptides HNB-92-169 and 116-169, tyr, derivatives of the C-terminal part of bovine myelin basic protein, sensitize rabbits for experimental allergic encephalomyelitis (EAE). Dissolving these peptides in heat-inactivated normal guinea-pig, human, or monkey serum immediately before emulsification with Freund's complete adjuvant (FCA) abrogated their disease-inducing activity. Dissolving them in homologous or autologous serum only slightly affected the encephalitogenicity.

The immune response against myelin basic protein in two strains of rat with different genetic capacity to develop experimental allergic encephalomyelitis

After challenge with guiena pig basic protein (GPBP) Lewis (Le) rats, which are homozygous for the immune response experimental allergic encephalomyelitis (Ir-EAE) gene, developed positive delayed skin tests against GPBP and the 43 residue encephalitogenic fragment (EF); in addition, Le rat lymph node cells (LNC) were stimulated and produced migration inhibitory factor (MIF) when incubated in vitro with these antigens. In contrast Brown Norway (BN) rats, which lack the Ir-EAE gene, did not develop delayed skin tests to EF and their LNC were not stimulated and did not produce MIF when incubated in vitro with EF. These observations indicate that the Ir-EAE gene controls a T-cell response against the EF. Le rats produced measurable anti-BP antibody by radioimmunoassay after primary challenge. Although no antibody was detectable in BN rats by radioimmunoassay, radioimmunoelectrophoresis indicated that a small amount of antibody was formed after primary immunization. After boosting intraperitoneally, both strains of rat exhibited a rise in anti-BP antibody; which was greater in Le rats. In both strains of rat the anti-BP antibody reacted with a portion of the molecule other than the EF. Since EF primarily evokes a T cell response, it is suggested that the EF portion of the BP molecule may contain a helper determinant in antibody production.

Alloantiserum-induced inhibition of migration inhibition factor production in immune response gene-controlled immune systems

We have previously demonstrated that alloantisera prepared by reciprocal immunization of strain 2 and strain 13 guinea pigs specifically block stimulation of in vitro DNA synthesis in genetically controlled systems. In order to determine whether this blockade extends to other T-lymphocyte functions, we examined the effect of alloantisera on the production of migration inhibition factor (MIF). (2 x 13)F(1) guinea pigs were immunized with a DNP derivative of the copolymer of L-glutamic acid and L-lysine (DNP-GL) and with DNP guinea pig albumin (GPA). The response to the former is controlled by a 2-linked Ir gene while that to the latter is mainly controlled by a 13-linked Ir gene. MIF production was assayed by an indirect procedure in which the migrating cell population lacked the histocompatibility antigen against which the alloantiserum was directed. Our results showed that anti-2 serum blocked MIF production by F(1) cells in response to DNP-GL but not DNP-GPA while anti-13 serum had the opposite effect. These experiments show that expression of a second major T-cell function is specifically blocked by alloantisera and suggest that Ir-gene products may act as antigen recognition substances on more than one type of T cell.