Expression of two cross-reactive idiotypes on mouse antibodies against bromelain-treated mouse erythrocytes.

Two cross-reactive anti-idiotype (Id) antibodies were previously prepared from sera of rabbits immunized with mouse monoclonal antibodies against bromelain-treated mouse erythrocytes (BrMRBC). Most of the anti-BrMRBC plaque-forming cells (PFC) were suppressed by either of the two anti-Id antibodies. The Id profiles of anti-BrMRBC PFC were almost identical among various cell populations in a strain, but different among various mouse strains. Mouse sera contained both of the Id-bearing immunoglobulins Ig, and a significant part of the Id-bearing Ig were eliminated by absorption with BrMRBC. Nude BALB/c mice were almost equal to normal BALB/c mice in the Id patterns of anti-BrMRBC PFC and in the concentrations of the Id-bearing Ig. The injections of anti-Id antibodies into suckling mice suppressed, specifically, the development of the B cells to produce the homologous Id-bearing Ig, but the injection of Id-bearing monoclonal antibodies barely affected Id expression. It is suggested that the two Id are encoded in germ-line genes of mice, and are expressed independently of each other and Id-anti-Id regulations by T cells or B cells.