Generation of anti-Neu-glycolyl-ganglioside antibodies by immunization with an anti-idiotype monoclonal antibody: A self versus non-self-matter

We have previously generated a murine anti-idiotype (Ab2) monoclonal antibody (mAb) to a murine Ab1 mAb, named P3, which selectively binds Neu-glycolyl (NeuGc)-sialic acid on several monosialo- and disialogangliosides, and also reacts with sulfatides and antigens expressed in human melanoma and breast tumors. This Ab2 mAb, designated as 1E10, induced anti-anti-idiotype antibodies (Ab3) in mice and cancer patients. These Ab3 generated by 1E10 mAb were characterized by bearing P3 mAb idiotopes (Ab3, Id+). But when the specificity of these Ab3 antibodies was tested, no specific humoral response against NeuGc-containing gangliosides was detected in sera from immunized mice. However, hyperimmune sera from melanoma and breast cancer patients vaccinated with this Ab2 mAb were able to react specifically with these gangliosides. The different expression of NeuGc-containing gangliosides in the normal tissues of mice and humans could explain these results. In order to demonstrate these findings in other animal species with a different NeuGc-sialic acid expression, we performed similar studies in monkeys and chickens. In monkeys, as in most mammals, NeuGc-containing gangliosides are self-antigens. In contrast, chickens, like humans, lack the expression of these antigens in normal tissues. Here we report that the antibody response against NeuGc-containing gangliosides induced by immunization with 1E10 mAb was completely different in both species. No specific antibody response against these gangliosides was detected in hyperimmune monkey sera. In contrast, a strong and specific Ab3 response against GM₃(NeuGc) and GM₂(NeuGc) gangliosides (Ab3, Ag+) was generated in chickens due to the administration of 1E10 mAb.