DISAPPEARANCE OF IGG2B AUTOANTIBODIES ASSOCIATED WITH RECOVERY FROM ANEMIA

Abstract

Mice immunized with cross-reacting rat erythrocytes develop autoimmune hemolytic anemia as indicated by hematological data and erythrocyte autoantibodies. With continued immunization the mice recover hematologically but remain Coombs'' positive. Coombs'' tests were performed using monospecific antisera to determine whether the recovery from anemia was associated with a change in the class or subclass of the autoantibodies produced. In both splenectomized mice and in unsplenectomized mice the following subclasses of erythrocyte autoantibodies were present: IgG1 [immunoglobulin G1], IgG2A and IgG2B. IgA autoantibodies were not detected, and IgM autoantibodies were only detected in splenectomized mice 1-3 wk after the IgG autoantibodies had appeared. After 6 immunizations the frequency of IgG2B autoantibodies decreased, and by the 10th immunization and thereafter IgG2B autoantibodies were not detected. The anemia is probably caused by IgG2B autoantibodies. The sudden exacerbation in the anemia that occurs in splenectomized mice is probably due to the production of IgM autoantibodies.