ALTERATION IN THE REACTIVITY OF SPHINGOMYELIN IN MITOGEN-STIMULATED LYMPHOCYTES

The antigens for a monoclonal antibody, VJ-41, established by alloimmu nization of B10.A(3R) mice with lymphocytes from B10.A(5R) mice and sc reening of its reactivity toward Con A-stimulated human T lymphocytes, were found to be phosphorylcholine-containing ceramides (sphingomyeli n) and disaturated fatty acyl glycerol (phosphatidylcholine, PC), but neither deacylated sphingomyelin nor unsaturated fatty acid-containing PC reacted with the antibody. Although the reactivity of disaturated fatty acyl PC increased with increasing chain length, that of sphingom yelin was stronger than that of di-20:0-PC. The binding of the antibod y to Con A-stimulated lymphocytes was inhibited by sphingomyelin-conta ining liposomes, but not by di-18:0-PC-containing ones, and the concen tration of sphingomyelin in Con A-stimulated human T-lymphocytes was t he same as that in non-stimulated ones, indicating that the reactivity of sphingomyelin in lymphocytes is altered by Con A-stimulation.