PROTECTIVE EFFECT OF VITAMIN-E ON LYMPHOCYTE GROWTH CAPACITY DURING INCUBATION IN-VITRO

Vitamin E, an essential lipid-soluble micronutrient, plays an importan t role in the immune system and serves as an immunostimulant in geriat ric subjects. Using an in vitro incubation to simulate aging processes , we find that vitamin E mitigates loss of growth capacity in lymphocy tes. Vitamin E presence during in vitro incubation did not affect sign ificantly the level of peroxidation, the effects of exogenous IL-2, PG E(2), or indomethacin, nor levels of IL-2 production. Thus, the preser vative effect on lymphocyte growth by vitamin E is not due primarily t o its antioxidant function or to interleukin-2 or prostaglandin effect s. The decreased growth capacity generated by in vitro incubation is a ccompanied by a variety of cellular alterations, including decreased C D5 surface antigen, enhanced suppression by adherent cells, and impair ed communication between lymphocytes and adherent cells. The decrease in CD5 surface antigen correlates inversely with the cell density requ ired for maximal cell proliferation, and the diminished CD5 levels wer e unaltered by vitamin E presence during the aging process. In contras t, protection of T-cell proliferative capacity by vitamin E in vitro c orrelates with diminished suppression by adherent cells and normalized interaction between lymphocytes and adherent cells.