Involvement of gangliosides in lymphocyte stimulation.

N4-Dinitrophenyl-L-2,4-diaminobutyric acid hydrazide was attached covalently to the aldehyde groups produced by periodate oxidate of bovine brain gangliosides and it was incorporated into mature thymocytes. High concentrations of antibodies to dinitrophenyl (DNP) or lower concentrations followed by protein A agglutinated the cells and stimulated DNA synthesis. Incubation of the thymocytes containing DNP-modified ganglioside with rabbit anti-DNP and fluorescein-labeled anti-rabbit IgG resulted in the formation of uniform rings on the cell surface, which subsequently developed into patches and caps. These results indicate that gangliosides may play a primary role in the lymphocyte activation process.