Modulation of the immune response by antigen-reactive lymphocytes after cultivation with gangliosides.

GM1 ganglioside isolated from mouse brain was found to be capable of inhibiting the thymocytotoxicity of AKR anti-Thy 1.2 antiserum and to a lesser extent anti-BAtheta antiserum. GD1b ganglioside of mouse brain and thymocytes inhibited the thymocytotoxicity of rabbit anti-BAtheta anti-serum for mouse thymocytes. When GM1 ganglioside, in the form of cholesterol-lecithin liposomes, was incubated with spleen cell cultures in the presence of SRBC, depressed anti-SRBC hemolytic plaque responses were observed. This effect could be neutralized by first absorbing the GM1 liposomes with anti-Thy-1.2 antibodies. The kinetics of GM1 numbers when the ganglioside was added even as late as the 4th day of culture. Results of experiments in which GM1 ganglioside was incubated with either bone marrow cells or with thymocytes suggest that the target cell for GM1 liposomes is the B lymphocytes.