Anti-Ro (SS-A) antibodies from Ro (SS-A)-immunized mice

Immunization of BALB/c mice with immunoaffinity-purified bovine or human Ro (SS-A) induces the production of antibodies reactive with Ro (SS-A). Fusion of spleen cells from the hyperimmunized mice to SP2/0 cells resulted in hybridoma cell lines that produced anti-Ro (SS-A) antibodies. Anti-Ro (SS-A) binding was established by solid-phase immunosorbent assay, immunoblotting, or RNA immunoprecipitation. Most of the anti-Ro (SS-A) antibodies bound to both human and bovine Ro (SS-A) in the solid phase, but only one of the monoclonal antibodies selectively bound to human Ro (SS-A); this suggests that there are species differences between the bovine and human Ro (SS-A) antigens. Indirect immunofluorescence studies demonstrated that most anti-Ro (SS-A) antibodies bound to cytoplasmic or nuclear HEp-2 cellular antigens, whereas others did not bind to fixed HEp-2 tissue culture cells. Nuclear staining of mouse substrates by one of the sera containing anti-Ro (SS-A) demonstrated that autoantibodies were induced by immunization with human Ro (SS-A).