Idiotypic cascades after injection of the monoclonal antibody OC125: a study in a mouse model. Induction of antibodies against OC125 and CA125 after immunization with an anti-CA 125 (MAb OC125) monoclonal antibody by activation of the idiotypic network.

By immunization of mice with the anti-CA 125 monoclonal antibody OC125, we tried to induce antibodies directed against the tumour-associated antigen CA125, via activation of the idiotypic network. Mice immunized by repeated administrations of F(ab')2-fragments of the OC125 antibody produced anti-idiotypic antibodies, imitating the original target antigen of the OC125. After induction of these anti-idiotypic antibodies (Ab2 beta) a murine IgG-anti-CA125 (Ab3) response was detected. The induction of idiotypic cascades offers the possibility of immunization against tumour-associated antigens, without using the original antigen and breaking antitumour tolerance.