Plasma lipoproteins and transferrin regulate the proliferation of a continuous T lymphocyte cell line.

Lipoproteins of hydrated densities < 1.063 g/ml, very low density (VLDL) and low density (LDL) lipoproteins, could both enhance and suppress the proliferation of T lympho- cyte cell lines. Enhancement and suppression were dependent on lipoprotein and transferrin concentrations. Enhancement oc- curred at low lipoprotein and high transferrin; suppression, at high lipoprotein and low transferrin. Lipoprotein suppression required a constituent of cell-conditioned medium as evidenced by the fact that lipoproteins did not suppress the replicative response of the IL-2-dependent murine cell line CTLL-2 to purified IL-2 but could suppress the response to cell-conditioned medium IL-2. For lipoprotein suppression and its relief by transferrin, both growth-regulating factors were required early in the cell cycle, suggesting that events important to progression through G1 are influenced. 1111 The data establish that the in- terplay between plasma lipoproteins, transferrin, and an un- known constituent of cell-conditioned medium can regulate the proliferation of T lymphocytes.-McCarthy, B. M., Y. Okano, T. Nakayasu, M. Macy, S. R. Watron, and J. A. I(. Harmony. Plasma lipoproteins and transferrin regulate the proliferation of a continuous T lymphocyte cell line. J. Lipid Res. 1987. 28: 1067 - 1077.