Polyunsaturated fatty acids are enriched in the plasma membranes of mitogen-stimulated T-lymphocytes.

Plasma membranes were purified from T-lymphocytes from rabbit thymus stimulated with concanavalin A. Lipids were extracted and the fatty acid composition of the individual phospholipid species was determined by gas-liquid chromatography. Compared to the plasma membranes derived from control cells, the plasma membranes from mitogen-stimulated cells were enriched in polyunsaturated fatty acids. This increase in unsaturation was found in phosphatidylcholine, phosphatidylinositol and phosphatidylserine, while the fatty acid composition of phosphatidylethanolamine was not significantly altered. The phospholipid composition remained almost unchanged during the period of stimulation. The molar ratio cholesterol to phospholipid was decreased. These changes in the lipid composition of plasma membranes from mitogen-stimulated T-lymphocytes are discussed with regard to functional implications.