Alloimmunization induces an autoantibody reactive with a common, cryptic antigen

C57BL/6 mice (haplotype H-2b) were alloimmunized by a classical protocol using repeated injections of DBA/2 spleen and liver cells (H-2d). The resulting polyclonal, hyperimmune antisera were highly cytotoxic to untreated and neuraminidase- (VCN)-treated DBA/2 spleen cells. An unexpected result was that the anti- H2d sera were also cytotoxic to VCN-treated C57BL/6 spleen cells. The cytotoxicity was limited to an IgM antibody and could be evoked by a single alloimmunization. The results demonstrate a new feature of the classical immune response, autoantibodies against a common, though cryptic murine antigen, designated Mo 1.