Comparative study of the kinetics of 3-hydroxy-3-methylglutaryl coenzyme A reductase and [14C]-acetate incorporation into cholesterol in human lymphocytes stimulated by phytohemagglutinin or sterol efflux.

The time course of sterol biosynthesis was compared after two different stimulations in normal human lymphocytes: culture either in the presence of phytohemagglutinin (PHA) or in a lipid-depleted medium (i. e. a condition which produces sterol efflux). Stimulation by PHA gives rise to an acute and rapid response in 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase activity and cholesterol synthesis. The sterol efflux induction produces a slower and milder response and the delayed sterol production consists mainly of lathosterol.