STRONG ANTIBODY REACTION AGAINST GLYCOSPHINGOLIPIDS INJECTED IN LIPOSOME-EMBEDDED FORMS IN β3GN-T5 KNOCKOUT MICE

It is known that mutant mice of the β-1,3-N-acetylglucosaminyltransferase gene (β3Gn-T5) respond well to T-cell dependent and independent antigens. Here, we examined the effectiveness of anti-ganglioside antibody generation by immunization of β3Gn-T5 mutant mice with liposome-embedded glycosphingolipids such as GD1a and GT1b. Consequently, the mutant mice showed a more efficient generation of anti-GD1a or anti-GT1b antibodies than wild-type mice in an enzyme-linked immunosorbent assay using sera during immunization. Thus, the β3Gn-T5 deficient mutant mice proved more responsive than wild-type mice to not only protein antigens, but also to carbohydrates in glycolipids. Furthermore, about 50% of monoclonal antibodies generated using splenocytes of the immunized mutant mice were of the IgG class. Besides general high responsiveness to proteins and glycolipids, it could be expected that the mutant mice of β3Gn-T5 would be useful in the generation of monoclonal antibodies towards lacto-/neolacto-series glycolipids, since these mutants lack lacto-/neolacto-series glycolipids. In fact, they showed a good serum response in immuno-fluorescence assay with cultured living cells when immunized by glycolipids extracted from ovarian cancer cell lines. These results suggested that β3Gn-T5 mutant mice are useful for the generation of anti-glycolipid antigens with lacto-/neolacto-core structures expressed in cancer cells.