ADAPTATION OF A CHOLESTEROL DEFICIENT HUMAN T-CELL LINE TO GROWTH WITH LANOSTEROL

A3.01 is a human T cell line previously shown to be defective in chole sterol biosynthesis. Following passage into serum-free medium, A3.01 c ells displayed a gradual decline in growth rate which correlated with a depletion of cellular cholesterol content and an accumulation of lan osterol and 24,25-dihydrolanosterol. At the point when cholesterol bec ame undetectable, the growth rate of serum-deprived cells was only one -tenth of the rate observed for serum-supplemented cells. The addition of low density lipoproteins (LDL) restored cellular cholesterol conte nt and resulted in a 7-fold higher growth rate, confirming that choles terol-deprivation was responsible for the slower growth in the absence of serum. Following prolonged culture in serum-free medium, A3.01 cel ls underwent a phenotypic change such that the cells achieved a growth rate which was similar to 65% of either LDL-supplemented or cholester ol-proficient cells. This apparent adaptation was not attributable to changes in either fatty acid or sterol composition. These results demo nstrate that while cholesterol is preferred, this lymphoid cell line c an adapt to the use of lanosterol to satisfy its membrane sterol requi rement. (C) 1994 Academic Press, Inc.