The specificity of nephritogenic antibodies: I. Evidence on anti-T-cell specificity in nephritogenic antibodies detected by cytotoxicity and MIF assays.

Heterologous antibodies directed to brushborder antigens of rat kidney tubules are nephritogenic in that an immediate immune complex glomerulopathy occurs after injection ot these antibodies into normal rats. Since previous observations suggested the presence of anti-T-cell specificity within these antibodies, we now compared the specificities of these antibodies with those of heterologous anti-rat thymocyte antibodies, using immunofluorescence (IF), cytotoxicity and migration inhibition (MIF) assays. The results suggest that anti-brushborder anti-serum contains anti-thymocyte specificities, while antithymocyte antiserum contains anti-brushborder specificity. These specificities could be removed selectively from both of the antisera by absorption with insoluble tissue extracts containing the appropriate antigens, i.e. thymocyte antigens or brushborder antigens respectively, indicating that two specificities are involved rather than only cross-reacting antibodies. Since it is unlikely for several other reasons that this feature is simply the result of an immunologic cross-reaction due to antibodies raised by immunization with purified kidney tissue antigens, this dual specificity of anti-brushborder antibody might play a role in the pathogenesis of experimental glomerulopathy.