Effects of enrichment of phosphatidylcholine liposomes with cholesterol or α-tocopherol on the response of lymphocytes to phytohemagglutinin

Abstract

Studies were performed to determine the ability of α-tocopherol and cholesterol to influence the effect of phosphatidylcholine (PC) liposomes on the blastogenic response of bovine peripheral blood lymphocytes (BPBL) to phytohemagglutinin (PHA). BPBL were cultured with liposomes having a molar ratio of cholesterol to PC (C/P) ranging from 0 to 2.0, a molar ratio of α-tocopherol to PC (E/P) of 1.0 and a molar ratio of cholesterol + α-tocopherol to PC [ ( C + E) P ] of 2.0 and 4.0. PC liposomes significantly suppressed BPBL blastogenic response to PHA. Cholesterol-rich (C/P ≥ 1.0) liposomes, α-tocopherol-rich (E/P = 1.0) liposomes and liposomes rich in cholesterol and α-tocopherol [ ( C + E) P ≥ 2.0 ] were able to completely reverse PC liposome suppression of BPBL. There was no molar ratio [C/P, E/P or (C + E)/P] that was able to enhance the blastogenic response of BPBL above the response obtained with PHA alone. The results suggest that the augmentation of PC liposomes rich in cholesterol, α-tocopherol and cholesterol with a-tocopherol (C/P and E/P ≥ 1.0) was equally capable of restoring normal responses in BPBL but did not enhance or suppress the response to PHA.