Natural murine autoantibodies and conventional antibodies exhibit similar degrees of antigenic cross-reactivity.

Splenic B cells from normal and autoimmune mice were transferred to MHC-compatible xid recipients. Monoclonal antibodies were secreted by the transferred B cells in splenic fragment cultures. These antibodies were evaluated for reactivity and cross-reactivity against a panel of six autoantigens and two conventional antigens using an ELISA assay. The autoantibodies and conventional antibodies produced in splenic fragment cultures by normal DBA/2 and autoimmune NZB B cells expressed similar degrees of antigenic cross-reactivity. Previous studies have demonstrated that ELISA assays of splenic fragment culture supernatants detect antibodies with affinities of 5 x 10(6) M-1 or greater. We therefore also analyzed the cross-reactivity of monoclonal antibodies derived from hybridomas. This permitted an assessment of antibodies with lower binding affinities. Cross-reactivity was detected more frequently among these hybridomas. Consistent with our earlier observations, hybridoma antibodies specific for conventional antigens exhibited cross-reactivity with a frequency similar to that of antibodies specific for autoantigens.