Induction of IgG antibodies against GD3 ganglioside in rabbits by an anti-idiotypic monoclonal antibody

Anti-idiotypic MAb were raised in syngeneic mice against a mouse MAb recognizing GD3 ganglioside (MAb R24). Two anti-idiotypic MAb, designated BEC2 and BEC3, recognized distinct determinants on MAb R24 that mapped near or within the GD3-binding site. New Zealand white rabbits, which ex-press GD3 on normal tissues, were immunized with either BEC2, BEC3, or control MAb FLOPC-21. All rabbits devel-oped high and equivalent titers of antibodies against mouse immunoglobulins. Immunization with BEC2 and BEC3 induced rabbit antibodies expressing R24 idiotype as demonstrated by their ability to inhibit BEC2 binding to R24. Antibodies (IgG and IgM) reacting with GD3 developed in five of eight rabbits immunized with BEC2 but not in rabbits immunized with BEC3 or with control MAb. Serum antibodies against GD3 did not cross-react with other gangliosides. These results show that MAb BEC2 can mimic GD3 ganglioside and can induce antibod-ies against GD3 ganglioside despite expression ofGD3 on normal rabbit tissue. (J. Clin. Invest. 1991. 88:186-192.) Key words: melanoma * immunization * internal image * glycolipi