Phospholipid methylation: a biochemical signal modulating lymphocyte mitogenesis.

Abstract

Phospholipid methylation in murine T [thymus-derived] lymphocytes but not B [bone marrow-derived] cells was stimulated by mitogenic lectins such as concanavalin [Con] A and phytohemagglutinin; the methylation was then returned to the control level by the concomitant activation of phospholipase A2. Parallelism between dose-response curves of Con A for phospholipid methylation and thymidine incorporation was found. Inhibition of synthesis or degradion of methylated phospholipids resulted in a decrease in the thymidine incorporation. Although prostaglandins such as the E and F series were the main products of arachidonic acid released by phospholipase A2 activation, inhibition of synthesis of these compounds by indomethacin did not reduce the thymidine incorporation significantly. The mitogenesis of murine T lymphocytes is apparently triggered by activation of phospholipid methyltransferase(s) and phospholipase A2.