The role of lipids in the interaction of Acholeplasma laidlawii cells with lymphocytes.

The role of A. laidlawii membrane lipids in the organism's interaction with mouse spleen lymphocytes is analyzed. A. laidlawii cells were grown in a lipid-poor medium with unsaturated fatty acids that allowed cells with different degrees of membrane lipid microviscosity to be obtained. The intensity of the binding of A. laidlawii cells and derived liposomes with lymphocytes depended directly on the degree of fatty acid unsaturation. Cholesterol incorporation into the A. laidlawii membrane reduced the fluidity of the lipid bilayer and decrease the binding activity. The intensity of cholesterol transfer from lymphocytes to A. laidlawii also depended on the degree of fatty acid unsaturation in A. laidlawii cells. Cells enriched with cholesterol took up considerably less of this sterol from lymphocytes. The loss of cholesterol as well as the enrichment of lymphocytes by A. laidlawii membrane fatty acids resulted in a decrease in the microviscosity of lymphocyte membrane lipids. It was concluded that the ability of A. laidlawii cells or derived liposomes to stimulate the transport of carbohydrates into lymphocytes depended on the degree of unsaturation of fatty acid incorporated into A. laidlawii. Cholesterol also decreased the stimulatory effect, probably by lowering carbohydrate carrier mobility.