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

Studies were performed to determine the ability of alpha-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 alpha-tocopherol to PC (E/P) of 1.0 and a molar ratio of cholesterol + alpha-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 greater than or equal to 1.0) liposomes, alpha-tocopherol-rich (E/P = 1.0) liposomes and liposomes rich in cholesterol and alpha-tocopherol [(C + E)/P greater than or equal to 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, alpha-tocopherol and cholesterol with alpha-tocopherol (C/P and E/P greater than or equal to 1.0) was equally capable of restoring normal responses in BPBL but did not enhance or suppress the response to PHA.