Polyspecific and autoreactive IgA secreted by hybridomas derived from Peyer's patches of vomitoxin-fed mice: characterization and possible pathogenic role in IgA nephropathy.

A total of 122 immunoglobulin (Ig)A-producing hybridoma clones were isolated from the Peyer's patches of vomitoxin-fed BALB/c mice and the resultant antibodies were characterized for their antigenic specificity and pathogenic potential. When reactivity was tested against a panel consisting of DNA, sphingomyelin, thyroglobulin, collagen, casein, cardiolipin and bovine serum albumin conjugates of phosphorylcholine, inulin and trinitrophenol that were representative of self and non-self antigens, approximately 95% of the monoclonal IgAs bound to at least one of the panel antigens and 80% bound to more than one antigen. The polyspecificity of some of the monoclonal IgAs was further suggested by demonstrating the capacity of one antigen to inhibit binding of monoclonal IgA to another antigen. Protein staining and Western blotting of gradient native polyacrylamide gels, indicated that trimeric IgA predominated in the isolated monoclonal IgAs. Repeated injections of mice with representative monoclonal IgAs induced microhaematuria in three of four of the clones tested but not IgA deposition in the kidney glomerulus. In addition, three of the four monoclonal IgAs caused IgG and C3 deposition in the kidney mesangium. These and previous results suggest that dietary vomitoxin promotes the polyclonal activation and expansion of IgA-secreting B cells at the Peyer's patch level and that resultant polyspecific, autoreactive IgA may contribute to kidney pathogenesis.