Cross-idiotypic reactions among anti-Rh (D) antibodies

In a series of experiments several idiotype-specific rabbit antisera produced against different IgG anti-Rh (D) antibodies reacted with other anti-Rh (D) antibodies and thus showed cross-idiotypic reactions. Some of the antisera agglutinated almost all types of anti-D-sensitized erythrocytes, whereas other idiotype-specific antisera agglutinated only a few anti-D-sensitized erythrocytes. Anti-D-antibodies showed several different cross-idiotypic reaction patterns. The cross-idiotypic antigens were, in most instances, localized to the heavy chains only. In a few cases, however, the cross-idiotypic antigens were dependent on the interaction between heavy and light chains.