In the present study we have examined the murine B cell response in anti-tubular basement membrane (alpha TBM) disease. Whereas only certain strains of mice are susceptible to the development of interstitial lesions after immunization with heterologous renal tubular antigen, all strains make anti-tubular basement membrane antibodies (alpha TBM-Ab), and all express the 3M-1 kidney antigen which is the target of disease. The magnitude of the alpha TBM-Ab response in serum and renal eluates, measured by radioimmunoassay against crude tubular antigen or affinity-purified 3M-1, also mapped independently of susceptibility. The fine specificity of epitope binding was further analyzed using a rat monoclonal alpha 3M-1 antibody to competitively inhibit the binding of renal eluate antibody to 3M-1. Maximum inhibition among nearly all tested strains ranged from 46 to 56% with no discernible difference between susceptible and nonsusceptible mice. Idiotypic representation of renal eluate alpha TBM-Ab was then evaluated by competitive inhibition using a polymorphic anti-idiotypic antisera. All mice examined possessed almost identical competitive inhibition patterns, indicating surprisingly similar idiotypic representation. Thus, in susceptible or nonsusceptible mice, neither the quantitative alpha TBM-Ab response, the epitopic fine specificity of that response, nor the idiotype of eluted alpha TBM-Ab serve as distinguishing markers for susceptibility to interstitial injury. Finally, passive transfer experiments with high-titered (greater than 1:10,000) alpha TBM-Ab from SJL mice were performed to test the hypothesis that alpha TBM-Ab alone may be sufficient for the induction of alpha TBM disease. Whereas this antiserum was capable of causing typical, severe alpha TBM disease in naive susceptible SJL mice, this treatment in allotype-identical, nonsusceptible B10.S(8R) mice was completely without effect. These data demonstrate, in conclusion, that, in the absence of appropriate susceptibility genes, alpha TBM-Ab are incapable of causing alpha TBM disease. The findings support previous observations that the ability of passively transferred alpha TBM-Ab to initiate interstitial injury is dependent on the host also expressing other susceptibility genes which promote the cooperative engagement of the cell-mediated immune response.

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