Correlations between membrane viscosity, serum cholesterol, lymphocyte activation and aging in man.

Membrane microviscosity, serum cholesterol and lymphocyte stimulation in man were examined in relation to aging. A direct correlation was found between the mole ratio of cholesterol to phospholipids in the serum and the membrane microviscosity of the peripheral blood lymphocyte membranes, both of which increase progressively with age. The increase in membrane microviscosity with age is also concomitant with the decrease in response of the lymphocytes to concanavalin A stimulation. The data suggest that increase in lymphocyte membrane microviscosity is a prominent factor which may lead to the overt reduction of proliferative responses of lymphocytes with aging.