Recognition of a leukemia-related antigen by an antiidiotypic antiserum to an anti-gp70 monoclonal antibody.

The possibility that receptors for retroviral gp70 share structural elements with the antigen-binding sites of anti-retroviral gp70 antibodies was investigated. A monoclonal antibody (1416) was produced that reacted with the gp70 of a cloned recombinant leukemogenic retrovirus, termed P1. An antiidiotypic antiserum raised to 1416 was tested for its ability to bind to the thymic leukemia induced by P1 (P1 Thy). A membrane structure was identified on the surface of P1 Thy that reacted with the antibody against the idiotypic determinant of 1416. A similar structure was identified on the surface of several different, independently derived murine leukemias of T cell, B cell, and erythroid lineage. The expression of the idiotype-like determinant on these leukemia cells was independent of the serological relatedness of their expressed retroviral envelope glycoproteins to P1 gp70. The determinant recognized by the antiidiotype was not detected on normal lymphoid cells. The recognition by the anti-(anti-gp70) idiotype of determinants on unrelated murine leukemias suggests that receptors for different leukemogenic viruses may share common structures.