Regulation of the immune response. II. Concomitant idiotope-specific enhancement and suppression can result in a phenotypically normal response

Idiotope-specific immunoenhancement or suppression was induced in C57BL/6 mice by the injection of physiological amounts (100 ng-10 micrograms) of monoclonal anti-idiotope antibody. As previously described, nanogram doses enhanced idiotope expression while a 10-micrograms dose of anti-idiotope antibody induced the activation of a population of Thy 1.2+, Lyt 1-, 2+ suppressors. Both positive and negative regulatory activities were confined to the non-mu, idiotope+ compartment of the plaque-forming cell response. Administration of intermediate doses of anti-idiotope antibody resulted in an immune state indistinguishable from that of naive mice. This apparently normal response was in fact the product of a simultaneous activation of balanced enhancing and suppressive activities. When treated with anti-Lyt 2 or Lyt 1 and complement, spleen cell populations taken from such phenotypically "naive" mice revealed latent idiotope-specific immunoenhancement or suppression, demonstrating the components of a functional regulatory equilibrium.     

Induction of neutralizing antibody in mice against poliovirus type II with monoclonal anti-idiotypic antibody

Syngeneic monoclonal anti-idiotope antibody Ab2,2-17C3SCC was raised against an idiotope on a protective monoclonal antibody with specificity for poliovirus type II. Ab2,2-17C3SCC detects a paratope-related interspecies IdX. Ab2,2-17C3SCC purified from supernatant fluids of hybridoma cells by protein A-Sepharose was injected into 4- to 6-wk-old BALB/c mice. The sera of the mice were screened for the expression of antibodies bearing the corresponding idiotope. Immunization of mice with Ab2,2-17C3SCC induced antibodies of complementary specificity. Furthermore, micro VN tests suggest that Ab2,2-17C3SCC can substitute for antigen in the induction of anti-polio neutralizing antibodies, and hence can function as a monoclonal anti-idiotypic vaccine.     

Analysis of the anti-alpha 1 leads to 3 dextran response with monoclonal anti-idiotype antibodies

The antibody response to alpha 1 leads to 3 dextran (DEX) in BALB/c mice consists of a family of closely related yet highly heterogeneous molecules. Although these antibodies have been previously characterized both idiotypically and structurally, detailed analysis of responding clones has not been possible using conventional anti-idiotype antibodies. Monoclonal syngeneic and allogeneic anti-idiotype antibodies (MAIDs) specific for anti-DEX antibodies were used in this study to dissect the serum antibody response to DEX in BALB/c mice. The constructed MAIDs showed considerable heterogeneity by isoelectric focusing and by their binding characteristics to a series of DEX specific myeloma and hybridoma proteins. The predominant heavy chain isotype of these MAIDs was gamma 1. These antibodies were used to identify individual idiotypic structures (IdI) on J558, or M104E as well as cross-reactive determinants common to both (IdX). Although both IdX and IdI MAIDs were obtained, IdI specific antibodies were obtained more frequently. BALB/c mice immunized with DEX produced antibodies expressing both IdI but in highly variable amounts. A large percentage of, but not all DEX specific antibody, could be accounted for by IdX bearing antibodies. Suppression of adult and neonatal mice by IdI specific MAIDs was effective with precise elimination of only those clones expressing IdI determinants leaving the total lambda bearing anti-DEX response intact. Suppression of adults and neonates by an IdX specific MAID resulted in a temporary and partial suppression of the total lambda bearing anti-DEX response along with total suppression of the IdX portion of the response. Unlike other systems these monoclonal antibodies produce only suppression, and under a variety of conditions enhancement of anti-DEX responses has not been observed.     

Serologic and topographic characterization of idiotopes on murine monoclonal anti-streptococcal group A carbohydrate antibodies

We have employed five spectrotypically distinct monoclonal anti-variable region antibodies in the definition and characterization of a set of idiotopes expressed on murine monoclonal antibodies specific for streptococcal group A carbohydrate (GAC). By evaluating which of a panel of monoclonal anti-GAC antibodies were bound by the various anti-idiotopes, we observed four distinct reactivity profiles for the five anti-idiotopes ranging from highly restricted (binding of the homologous anti-GAC monoclonal antibody only) to broadly cross-reactive (binding of 18 of the 38 IgG3 anti-GAC antibodies). With N-acetyl-D-glucosamine and soluble GAC used as haptens, this spectrum of reactivity profiles was paralleled by a gradient of susceptibility to hapten inhibition of anti-idiotope binding to idiotope. The degree of cross-reactivity exhibited by a given anti-idiotope was found to be inversely related to its susceptibility to hapten inhibition. The topographic relationships among the idiotopes, defined by the results of competitive binding assays, were suggestive of a linear idiotope map spanning the variable region from the antigen-binding site to the vicinity of the constant region. Additional data from competitive inhibition assays with isolated and recombined H and L chains from a prototype monoclonal anti-GAC antibody (HGAC 39), and from isoelectric focusing of whole or reduced and alkylated HGAC 39, suggested that one of the idiotopes was located, at least primarily, on the VL domain.     

Reexpression of a T15 idiotope on variant immunoglobulins after the binding of another anti-idiotopic antibody

The phosphorylcholine (PC)-binding myeloma protein TEPC15 (T15) contains several distinct idiotopic determinants that are detectable with monoclonal anti-idiotopic antibodies. This study focuses on one of these anti-idiotopes, designated B24-44, which binds to a site near the T15 paratope. Another anti-idiotope, B36-82, recognizes an idiotope that is distant from the paratope. Two PC-binding immunoglobulins, 7-22 and 140.7C6, that differ from T15 by one to three amino acids have selectively lost their reactivity with the anti-idiotope, B36-82. However, the B36-82 binding was restored when B24-44 was first allowed to react with these immunoglobulins. The binding of B24-44 as well as the restoration of the B36-82 site was specifically inhibited by PC-protein conjugates. Competition experiments suggested that the newly induced B36-82 determinant is in the same location as the B36-82 binding site on T15. These data indicate that the binding of anti-idiotopic determinants to an immunoglobulin can alter the protein structure and create new determinants.     

Control of macrophage Ia expression in neonatal mice--role of a splenic suppressor cell

The control of macrophage expression of I region-associated antigens (Ia) in neonatal mice was studied by comparing responses of neonatal and adult mice to immune vs nonimmune stimuli. Adults generated peritoneal exudates rich in Ia-bearing macrophages in response to i.p. injection of live Listeria monocytogenes, Listeria-immune T cells, and heat-killed Listeria, or a soluble mediator termed macrophage Ia-recruiting factor (MIRF). Neonates failed to respond to these stimuli. In contrast, both neonates and adults generated Ia-negative peritoneal exudates when stimulated with thioglycollate. A neonatal spleen cell that blocked the response of adults both to immune T cells and heat-killed Listeria and to MIRF was identified and characterized. Some of the suppressor cells appeared to be early precursors of the phagocytic lineage that develop into mature monocyte-macrophages. Suppression was apparently mediated by metabolites of arachidonic acid since indomethacin and aspirin in vivo blocked the effect. Similar suppressor activity was found in adult bone marrow and in adult resident peritoneal exudate cells. Thus, the phagocytic line autoregulates its surface expression of Ia in both neonatal and adult mice. This mechanism becomes particularly pointed during early development and could contribute to the lack of immunity during ontogeny.     

Syngeneic monoclonal internal image anti-idiotopes as prophylactic vaccines

A syngeneic monoclonal anti-idiotope that behaves as an internal image of the mammalian reovirus type 3 cellular attachment protein (viral hemagglutinin) was used in the syngeneic host for the induction of a prophylactic anti-viral antibody response. These studies were performed without the aid of co-stimulation by viral antigens. The high stringency of this system enables us to define the maximum constraints on the use of anti-idiotopes as anti-viral vaccines. We have used the murine BALB/c monoclonal IgM anti-idiotope 87.92.6 to study the idiotope and antigen specificity, kinetics, dose dependence, adjuvant, carrier, and valency requirements of anti-idiotope-induced anti-viral antibody responses. These studies show that the production of high titer neutralizing antibody requires a lengthy (60 day) immunization protocol, which includes the use of adjuvant and multivalent anti-idiotope, and is dependent on anti-idiotope concentrations of greater than 50 micrograms. When administered in this manner anti-idiotope can stimulate serotype-specific antibody responses across species barriers at levels comparable with those obtained after inoculation with virus. The practical efficacy of these reagents and procedures is documented by the ability of maternal immunization with anti-idiotope to confer complete protection in neonates from a potentially lethal reovirus type 3 viral infection.     

Modulation of the murine immune response to streptococcal group A carbohydrate by immunization with monoclonal anti-idiotope

Using monoclonal anti-idiotopes with previously defined specificities for the variable (V) domain of HGAC 39, a monoclonal antibody against streptococcal group A carbohydrate (GAC), we have studied the effect of anti-idiotope on an anticarbohydrate immune response. Anti-IdI-3a and anti-IdI-3b are anti-idiotopes which recognize binding site-associated determinants, whereas anti-IdX recognizes a framework-associated determinant on the HGAC 39 V kappa domain. Each of three anti-idiotopes elicited a specific idiotope response, as measured by inhibition radioimmunoassay, in A/J and C57BL/6J mice. A single immunization with conjugated anti-IdI-3a elicited an idiotope(+), GAC-binding(+) response in C57BL/6J and (BALB/c X CBA/N)F1 male mice, but not in A/J or (CBA/N X BALB/c)F1 male, X-linked immunodeficient mice. When C57BL/6J mice immunized initially with anti-idiotope were further treated with group A vaccine, those receiving anti-IdX had the greatest increase in anti-GAC activity. Stimulation of an anticarbohydrate response with anti-idiotope may therefore be enhanced by selecting anti-idiotopes against both binding site- and framework-associated determinants.     

Idiotype vaccines against human T cell acute lymphoblastic leukemia. I. Generation and characterization of biologically active monoclonal anti-idiotopes

A murine monoclonal anti-tumor antibody termed SN2 (Ab1), isotype IgG1-kappa, that defines a unique human T cell leukemia-associated cell-surface glycoprotein, gp37 (m.w. 37,000), was used to generate monoclonal anti-idiotype antibodies (Ab2) in syngeneic BALB/c mice. The Ab2 were screened on the basis of their binding to the F(ab')2 fragments of SN2 and not to the F(ab')2 of pooled normal BALB/c mice sera IgG1 or to an unrelated BALB/c monoclonal antibody of the same isotype. Fifteen Ab2, obtained from two fusions, were specific for the SN2 idiotope and not against isotype or allotype determinants. To find out whether these Ab2 are directed against the paratope of SN2, the binding of radiolabeled SN2 to leukemic MOLT-4 and JM cells which contain gp37 as a surface constituent was studied in the presence of these anti-idiotopes. Clone 4EA2 inhibited the binding 100% at a concentration of 50 ng and 4DC6 inhibited 90% at a concentration of 250 ng. A third clone 4DD6 gave about 50% inhibition. Similar was the inhibition of SN2 binding to insolubilized MOLT-4 antigen or cell membrane preparation. The binding of SN2 (Ab1) to 4EA2 and 4DC6 was also inhibited by semipurified preparation of gp37 antigen. These results demonstrate that at least two of the anti-idiotope antibodies are binding either at or near the binding site idiotope of SN2. Next, the purified Ab2 was used to immunize syngeneic mice to induce antibody binding to MOLT-4 cells or gp37. Sera from mice immunized with 4EA2 and 4DC6 coupled to keyhole limpet hemocyanin contained antibodies which bind to semipurified gp37 antigen and MOLT-4 cells. Immune sera inhibited the binding of iodinated Ab2 and Ab1 indicating that an anti-anti-idiotopic antibody (Ab3) in mice shares idiotopes with Ab1 (SN2). Also, the binding of iodinated Ab2 to Ab1 was inhibited by rabbit antisera specific for gp37. Collectively, these data suggest that anti-idiotype antibodies 4EA2 and 4DC6 may be useful in the generation of idiotype vaccines against human T cell leukemia.     

The human and murine influenza-specific B cell repertoires share a common idiotope

We have dissected the human influenza-specific B cell repertoire by performing Epstein-Barr virus (EBV) limiting dilution analysis of lymphocytes obtained from donors before and after immunization with a commercially available influenza vaccine. In addition to an analysis of precursor frequency and light chain diversity, we studied sera and culture supernatants containing human anti-influenza antibodies with a panel of murine monoclonal antibodies specific for idiotopes identified on murine anti-PR8 and anti-X-31 antibodies. An idiotypic specificity present on the X-31-specific murine monoclonal PY206 has previously been shown to be shared by murine antibodies specific for PR8, X-31, and other influenza viruses. We observed little correlation among the following parameters: anti-viral titer, serum idiotope content, precursor frequency and immune status. More interestingly, there was a striking predominance of human influenza-specific antibodies that utilized lambda light chains. In addition, 12 of 26 human anti-influenza monoclonals strongly inhibited the binding of one of the murine anti-idiotopes to the labeled murine antibody, PY206. This is the same idiotope that is shared among murine antiinfluenza antibodies and all six individuals studied contained clones reactive with this anti-idiotope. Seven of these 12 idiotope-positive human antibodies gave partial cross-reactivity in a second anti-idiotypic system. These observations imply that a significant level of homology exists between the binding sites of human and murine influenza-specific antibodies and suggest that idiotypic manipulation of the human immune response to influenza virus may have important therapeutic implications.     

Structural characterization of idiotopes by using antibody variants generated by site-directed mutagenesis

Four anti-idiotopic mAB, 107, MB, AI, and AD8, react with mouse hybridoma protein 36-65 specific for the hapten p-azophenylarsonate. The four antiidiotypic antibodies do not react with hybridoma protein 36-71, a somatically mutated variant of 36-65 whose H and L chain V region sequence differs at 19 amino acid positions. To determine which regions of 36-65 are important for the interaction with each of the four anti-idiotypic antibodies, variants of 36-65 containing one or more of the 36-71 substitutions were generated by oligonucleotide-directed mutagenesis of the rearranged 36-65 H chain V region gene, followed by expression of mutant proteins containing either the 36-65 or the 36-71 L chain in transfected hybridoma cells. Idiotypic characterization of the mutant proteins showed that reactivity correlates with the 36-65 H chain, but some contributions from the 36-65 L chain come into play. In the 36-65 H chain V region, idiotopes were mapped to the first and third complementarity-determining regions for anti-idiotypic antibodies 107, MB, and AI, and to all three complementarity-determining regions for anti-idiotypic antibody AD8. The binding of all four anti-idiotypic antibodies to hybridoma protein 36-65 was hapten inhibitable. However, a comparison between the effect of individual 36-71 substitutions on idiotope expression and their effect on Ag-binding affinity suggests that none of the four anti-idiotypic antibodies bodies mimics the structure of Ag.     

Tumor-specific idiotopes on suppressor factors and suppressor cells revealed by monoclonal anti-idiotope antibodies

Two monoclonal anti-idiotope antibodies, previously found to induce tumor-specific cell-mediated immunity in mice, were examined for their relationship to tumor-associated suppressor factors (SF), produced in culture by spleen cells from tumor-bearing mice or present in sera from such mice. A leukocyte adherence inhibition assay was used to detect cellular immunoreactivity to tumor antigens and its inhibition by SF, using peritoneal cells from mice bearing tumor or sensitized with anti-idiotope antibody. The SF were specifically absorbed by the corresponding anti-idiotope antibodies coupled to a solid phase and were recovered by elution. They were also specifically neutralized by the addition of the respective antibodies to the assay system. Anti-idiotope antibody, used with complement to pretreat spleen cells from tumor-bearing mice, prevented these cells from producing SF in culture. Tumor antigen-reactive effector cells, suppressor cells, and SF thus share similar idiotopes, permitting their respective functions to be modulated by appropriate anti-idiotopes.     

The developmental patterns of B cell precursors distinguishing between environmental and nonenvironmental forms of phosphocholine.

We have analyzed the developmental patterns of two groups of B cell precursors in nonimmunized BALB/c mice with respect to their relative proportions, absolute frequencies, V gene usage, fine specificity, and avidity for antigen. One group of B cells (group I) secretes antibodies specific for PC and PC-containing bacteria, whereas the other group (group II) produces antibodies recognizing only nonenvironmental PC-protein conjugates. A marked shift in the proportions of group I and group II occurs during ontogeny: while the group I B cells dominate (greater than 85%) the adult antibody repertoire, the group II B cells have equal representation in neonatal mice from Days 1 to 7, and remain as a significant portion until 2 weeks of age. Examination of the absolute frequencies of group I and group II B cells revealed that the frequency of group II B cells remained relatively stable throughout ontogeny, whereas group I B cells expanded rapidly after 7 days of age to predominate in the adult. Genetic analysis indicated that early group I antibodies were encoded by VH and VL genes different from adult group I antibodies which are mostly encoded by a single VH (S107) and VL (V kappa 22) gene combination (the T15 idiotype). On the other hand, early group II antibodies used VH genes comparable to their adult counterparts. The majority of early group I antibodies have lower avidity for PC than adult T15+ antibodies, whereas the avidity of neonatal group II antibodies varies considerably and is comparable with that of the adult group II antibodies. Our results suggest that the ontogeny of phosphocholine-specific B cells may be regulated according to their fine specificity rather than to their avidity or V gene usage.     

Idiotype matching: correlation of expression of protective idiotype in sera with survival of tumor mice

A monoclonal anti-Id, 2F10, has previously been shown to protect against transfer of L1210/GZL tumor cells in DBA/2 mice and also to have therapeutic effects in mice with growing tumor. In this study we have measured expression of an idiotope which reacts with a tumor-protective anti-idiotypic antibody, 2F10, in the sera of mice bearing the L1210/GZL tumor. The levels of antibodies binding to 2F10, referred to as the "2F10 idiotope," are different in individual mice and also fluctuate over time. A statistical analysis demonstrated a significant correlation between these changes in 2F10 levels in mice with tumors and their survival times. Increasing 2F10 idiotope in sera of tumor mice correlated with long-term survival, whereas a decreasing trend was found in mice which died shortly after tumor transfer. Correlations between the 2F10 idiotope and survival were observed in groups of mice which had received surgery, cyclophosphamide, a combination of cyclophosphamide and anti-idiotype, or no treatment at all. No correlation between a nonrelated idiotope and survival was noted. Although 2F10 is an idiotope expressed by an anti-tumor-associated Ag antibody, the correlation between anti-tumor-associated Ag titers and survival was significantly lower than that between the 2F10 idiotope and survival. This demonstrates that 2F10 is preferentially associated with antibodies which are involved in tumor regression. Thus, the 2F10 idiotope in sera of tumor-bearing mice has predictive value for survival and tumor regression.     

Idiotope vaccine against Streptococcus pneumoniae. A precursor study

An analysis of nominal vs idiotope antigen-induced B cell precursors was performed in A/St mice. With the use of the splenic fragment culture system, the quantity and quality of B cell precursors responding to two anti-idiotope carrier antigens (4C11 hemocyanin and F6 hemocyanin) and nominal antigen (phosphorylcholine-hemocyanin) were compared. In addition, the effect of priming with anti-idiotope-carrier antigens on B cell precursors responding to phosphorylcholine-hemocyanin was determined. We found that one anti-idiotope-carrier antigen, 4C11-hemocyanin, and phosphorylcholine-hemocyanin stimulated similar subpopulations of primary B cells. However, the B cell population stimulated by F6-hemocyanin, the other anti-idiotype complex, was distinct. Furthermore, priming with certain idiotope antigens can direct the phosphorylcholine-hemocyanin response into the expression of idiotypes that may be the most effective in protective immunity. Our results provide essential information for the rational design of idiotype vaccines by clarifying the dynamic relationship of the B cell precursor repertoire with the in vivo antibody response in the response to nominal and idiotope antigens.     

Suppressor T cells: presence in mice rendered tolerant by neonatal treatment with anti-receptor antibody or antigen.

Specific tolerance to phosphorylcholine (PC) was induced in BALB/c mice by two methods. Neonatal mice received a single injection of either: 1)PnC, the C-polysaccharide from S. pneumoniae, R36a vaccine which has PC as a major antigenic determinant or 2) ARA, an homologous antibody directed against the receptor for PC. Spleen cells from animals treated as neonates with either PnC or ARA were specifically suppressed for the response to PC antigens in vitro. In addition, cells from either group of unresponsive animals co-cultured with spleen cells of normal BALB/c mice markedly suppressed the response of the normal cells to PC. Greater than 90% inhibition of the plaque-forming cell response was obtained when unresponsive cells were mixed with normal cells in ratios of 1:1 or greater. Equal numbers of cells from animals made unresponsive by PnC or ARA produced an equivalent degree of suppression. Neither supernatants of cultures nor sera of animals of either unresponsive group suppressed the response of normal spleen cells to PC. Suppression by cells from both groups of tolerant mice was eliminated by treatment with anti-Thy 1.2 serum and C. Presumably, a common cell is responsible for suppression caused by cells from mice made unresponsive by either procedure.     

Relationships between liquid- and solid-phase antibody association characteristics: implications for the use of competitive ELISA techniques to map the spatial location of idiotopes

A liquid-phase assay system based on small-zone size-exclusion chromatography was used to examine the binding of a monoclonal anti-idiotopic antibody, F6, to its idiotope on the murine plasmacytoma IgA, TEPC-15. Chromatographic behavior revealed a strong association between T-15 and F6, which was previously characterized by solid-phase immunoassay as recognizing a nonbinding site epitope of the T-15. This chromatographic pattern suggests that the inability of the hapten phosphorylcholine to inhibit the anti-idiotope:idiotope relationship in solid-phase immunoassay might be equally explained by the low affinity of the hapten relative to the high affinity of the anti-idiotope antibody. Bivalent interactions between solid-phase IgA and liquid-phase IgG should enhance the binding of the anti-idiotope to an extent that would prevent the hapten from dissociating the complex. Under these solid-phase assay conditions, observation of hapten inhibition may, in some cases, indicate site specificity, but absence of inhibition cannot be interpreted. Computer simulations of solid-phase hapten inhibition scenarios were used to evaluate the qualitative nature of binding inhibition profiles expected under various conditions of liquid- and solid-phase reactant affinities and concentrations. The apparently unusual inhibition curves previously observed in the T-15:anti-T-15 studies in which the degree of binding inhibition by hapten appeared to be independent of anti-idiotope concentration may be predictable in cases of excess solid-phase epitope; the plateau inhibition value is a function of relative affinity constants and concentrations of solid-phase and inhibitor components. The results additionally suggest that the affinity of a liquid-phase antibody may modulate the effective concentration of solid-phase epitope.     

Suppression of natural killer cytolytic activity in mice undergoing pulmonary granulomatous inflammation

CBA/J mice undergoing pulmonary granulomatous inflammation exhibited depressed NK cytolytic activity. Granulomas induced by i.v. embolization of Schistosoma mansoni eggs (hypersensitivity type) or Sephadex beads (foreign body type) both caused reduced NK activity, although hypersensitivity granulomas induced a significantly higher level of NK suppression. Kinetic analysis of hypersensitivity lesions at 4, 8, 16, and 32 days post-embolization indicated that NK activity was significantly suppressed by day 8, maximally suppressed by day 16 (at the peak of the inflammatory response) then returned to near control values by day 32 (as the granulomas resolved). Suppression of NK activity ranged from three- to 15-fold in different experiments. NK cells obtained from both spleen and peripheral blood demonstrated reduced NK activity with kinetic patterns similar to the granuloma NK cells. Suppression was not due to reduced splenic NK cells as the frequency of YAC-1 binding cells, as well as asialo GM1+ or laminin+ cells remained constant over the entire study period. Suppression of NK activity did not appear to be due to serum components or suppressor cells present in the spleen preparations. However, the suppression of NK activity could be reversed by overnight incubation of spleen cells at 25 or 37 degrees C or daily treatment of the mice with indomethacin. Suppression also appeared relatively specific for NK cells as the generation and expression of cytotoxic T lymphocyte activity was not affected.     

Activation of regulatory cells suppresses experimental allergic encephalomyelitis via secretion of IL-10

Suppression of CD4+ Th1 cell-mediated autoimmune disease via immune deviation is an attractive potential therapeutic approach. CD4+ Th2 T cells specific for myelin basic protein, induced by immunization of young adult male SJL mice, suppress or modify the progression of CNS autoimmune disease. This report demonstrates that activation of non-neuroantigen-specific Th2 cells is sufficient to suppress both clinical and histological experimental allergic encephalomyelitis (EAE). Th2 cells were obtained following immunization of male SJL mice with keyhole limpet hemocyanin. Transfer of these cells did not modify EAE, a model of human multiple sclerosis, in the absence of cognate Ag. Disease suppression was obtained following adoptive transfer and subcutaneous immunization. Suppression was not due to the deletion of myelin basic protein-specific T cells, but resulted from the presence of IL-10 as demonstrated by the inhibition of Th2-mediated EAE suppression via passive transfer with either anti-IL-10 or anti-IL-10R mAb. These data demonstrate that peripheral activation of a CD4+ Th2 population specific for an Ag not expressed in the CNS modifies CNS autoimmune disease via IL-10. These data suggest that either peripheral activation or direct administration of IL-10 may be of benefit in treating Th1-mediated autoimmune diseases.