Adjuvant arthritis (AA) is an experimental model of autoimmune arthritis that can be induced in susceptible strains of rats such as inbred Lewis upon immunization with CFA. AA cannot be induced in resistant strains like Brown-Norway or in Lewis rats after recovery from arthritis. We have previously shown that resistance to AA is due to the presence of natural as well as acquired anti-heat shock protein (HSP) Abs. In this work we have studied the fine specificity of the protective anti-HSP Abs by analysis of their interaction with a panel of overlapping peptides covering the whole HSP molecule. We found that arthritis-susceptible rats lack Abs to a small number of defined epitopes of the mycobacterial HSP65. These Abs are found naturally in resistant strains and are acquired by Lewis rats after recovery from the disease. Active vaccination of Lewis rats with the protective epitopes as well as passive vaccination with these Abs induced suppression of arthritis. Incubation of murine and human mononuclear cells with the protective Abs induced secretion of IL-10. Analysis of the primary and tertiary structure of the whole Mycobacterium tuberculosis HSP65 molecule indicated that the protective epitopes are B cell epitopes with nonconserved amino acid sequences found on the outer surface of the molecule. We conclude that HSP, the Ag that contains the pathogenic T cell epitopes in AA, also contains protective B cell epitopes exposed on its surface, and that natural and acquired resistance to AA is associated with the ability to respond to these epitopes.

The inheritance of particular alleles of major histocompatibility complex class II genes increases the risk for various human autoimmune diseases; however, only a small percentage of individuals having an allele associated with susceptibility develop disease. The identification of allelic variants more precisely correlated with disease susceptibility would greatly facilitate clinical screening and diagnosis. Oligonucleotide-primed gene amplification in vitro was used to determine the nucleotide sequence of a class II variant found almost exclusively in patients with the autoimmune skin disease pemphigus vulgaris. In addition to clinical implications, the disease-restricted distribution of this variant should provide insight into the molecular mechanisms underlying associations between diseases and HLA-class II genes.

The role of DNA as the target for pathogenic lupus autoantibodies in systemic lupus erythematosus is equivocal and renal damage may be due to cross-reactivity of lupus Abs with glomerular components. We have previously shown that lupus autoantibodies bind to the laminin component of the extracellular matrix. In the present work, we have analyzed the fine specificity of the interaction of pathogenic murine lupus autoantibodies with this molecule and the effect of inhibiting their binding to laminin during the course of the disease. We have found that pathogenic murine lupus autoantibodies react with a 21-mer peptide located in the globular part of the α-chain of laminin. Immunization of young lupus-prone mice with this peptide accelerated renal disease. Analysis of transgenic, congenic, and RAG-1−/− mice confirmed the importance of this epitope in the pathogenesis of lupus renal disease. We have synthesized a panel of peptides that cross-react with the anti-laminin Abs and have found that the binding of lupus autoantibodies to the extracellular matrix could be inhibited in vitro by some of these competitive peptides. Treatment of MRL/lpr/lpr mice with these peptides prevented Ab deposition in the kidneys, ameliorated renal disease, and prolonged survival of the peptide-treated mice. We suggest that laminin components can serve as the target for lupus Abs. The interaction with these Ags can explain both the tissue distribution and the immunopathological findings in lupus. Moreover, inhibition of autoantibody binding to the extracellular matrix can lead to suppression of disease.

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The autoimmune dermatologic disease pemphigus vulgaris (PV) is associated with the HLA serotypes DR4and DRw6. Susceptibility to PV could be conferred either by sequences shared between the DR4 and DRw6 haplotypes or by different sequences in these haplotypes. We have examined the distribution of DR and DQ fl-chain and DQ a-chain alleles in PV patients and in control subjects by hybridization with oligonucleotide probes and sequence analysis of in vitro ampli- (8). In population studies, PV is strongly associated with the serotypes HLA-DR4 and HLADRw6 (9, 10), with <5% of the patients possessing neither marker. Disease associations with two different HLA haplotypes could mean either that these two haplotypes share a common allele or epitope or that different alleles in the two haplotypes can confer disease susceptibility.As noted above, molecular analysis of serologically defined class II haplotypes (e.g., DR4 and DRw6) has revealed significant variation at the DR and DQ loci. Sequence analysis of class II genes from various haplotypes demonstrated that a DR/I epitope at amino acid positions 67-71 (termed here "IDE", based on one-letter symbols for Ile-67, Asp-70, and Glu-71) was shared between a subset of DR4 haplotypes ("DwlO") (11) and a subset of DRw6 haplotypes (DRw13) (ref. 12 and unpublished data). This observation suggests that these shared polymorphic residues of the DR,8I chain, which determines the DR specificity, may contribute to PV autoimmunity and account for both the DR4-and the DRw6-associated susceptibility. However, Szafer et al. (10) reported that specific restriction-fragment length polymorphisms (RFLPs) detected with a DQP cDNA probe subdivided the DR4 and DRw6 haplotypes and showed significantly higher associations with PV than did the serologic markers. Analysis of allelic coding-sequence variation in patients and in controls is needed to identify the putative class II alleles or epitopes that contribute to PV.Sequence analysis of DR,3I, DRfIII, and DQB alleles from three U.S. DR4+ PV patients (DR4/4, -4/5, and -4/5) revealed that all the patients had the Dw1O DRf3I allele (13) found in only 10o of U.S. DR4+ controls (14). Further, three of the four DQP alleles from the DR4 haplotypes were the DQB3.2 allele present in 60-80% of control DR4 haplotypes. These sequence data, although obtained from only three patients, suggest that, for the DR4 susceptibility to PV, the Dw1O DR,6I allele may contribute to autoimmunity but that the DQ, allele does not. These data were obtained by using the polymerase chain-reaction (PCR) method for the in vitro amplification of specific genomic sequences (15)(16)(17).We report here the use of sequence-specific oligonucleotide (SSO) probes to determine the distribution of DR4 DRBI and DQB alleles in a panel of PV patients and controls. The frequency of the IDE sequence in patient and control DRw6 haplotypes was also determined, to test the "shared epitope" model of PV susceptibility. In addition, we describe the Abbreviations: PV, pemphigus vulgaris; ...