ALTERATION IN THE REACTIVITY OF SPHINGOMYELIN IN MITOGEN-STIMULATED LYMPHOCYTES

The antigens for a monoclonal antibody, VJ-41, established by alloimmunization of B10.A(3R) mice with lymphocytes from B10.A(5R) mice and screening of its reactivity toward Con A-stimulated human T lymphocytes, were found to be phosphorylcholine-containing ceramides (sphingomyelin) 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 sphingomyelin was stronger than that of di-20:0-PC. The binding of the antibody to Con A-stimulated lymphocytes was inhibited by sphingomyelin-containing liposomes, but not by di-18:0-PC-containing ones, and the concentration of sphingomyelin in Con A-stimulated human T-lymphocytes was the same as that in non-stimulated ones, indicating that the reactivity of sphingomyelin in lymphocytes is altered by Con A-stimulation.