Journal of Lipid Research, Vol 28, 1067-1077, Copyright © 1987 by Lipid Research, Inc.
Plasma lipoproteins and transferrin regulate the proliferation of a continuous T lymphocyte cell line
BM McCarthy, Y Okano, T Nakayasu, M Macy, SR Watson and JA Harmony
Department of Pharmacology and Cell Biophysics, University of Cincinnati, OH 45267-0575.
Lipoproteins of hydrated densities less than 1.063 g/ml, very low density
(VLDL) and low density (LDL) lipoproteins, could both enhance and suppress
the proliferation of T lymphocyte cell lines. Enhancement and suppression
were dependent on lipoprotein and transferrin concentrations. Enhancement
occurred 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. The data establish that the interplay between
plasma lipoproteins, transferrin, and an unknown constituent of cell-
conditioned medium can regulate the proliferation of T lymphocytes.