Journal of Experimental Medicine, Vol 146, 1791-1803, Copyright © 1977 by Rockefeller University Press
Inhibition of lymphocyte proliferation stimulated by lectins and allogeneic cells by normal plasma lipoproteins
JH Morse, LD Witte and DS Goodman
Lipoproteins, isolated by sequential flotation at densities 1.006, 1.019,
1.063, and 1.21, were examined for their ability to inhibit human
lymphocytes stimulated by allogeneic cells and by lectins
(phytohemagglutinin-P and concanavalin A). All the classes of normal plasma
lipoproteins inhibited lymphoproliferation when peripheral blood
lymphocytes were cultured in autologous, heterologous, or lipoprotein-
deficient plasma (d greater than 1.21). The rank order of inhibitory
potency was intermediate density lipoprotein (IDL) greater than very low
density lipoproteins (VLDL) greater than low density lipoproteins (LDL)
greater than high density lipoproteins (HDL), regardless of the mode of
stimulation. The concentrations of IDL, VLDL, and LDL required for complete
inhibition of stimulated lymphoproliferation were considerably below the
levels of each of these lipoproteins normally found in human plasma. In
addition, the concentration of HDL required for 50-90% inhibition was in
the range of HDL levels normally found in human plasma. Moreover, at
relatively higher concentrations, lipoproteins suppressed the incorporation
of [3H]thymidine into DNA below the levels seen with reseting, unstimulated
lymphocytes. The results suggest that circulating lymphocytes may normally
be highly suppressed by the combined effects of all the endogenous
lipoproteins and that the lipoproteins may play important roles in vivo in
modulating lymphocyte functions and responses.
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