Effect of Plasma Lipoproteins on Natural Killer Cell Activity in the Elderly Population

Background. Natural killer (NK) cells possess spontaneous cytotoxicity against tumors and virus-infected cells to play a major role in immunosurveillance and defense against the development of cancer, as well as bacterial and viral infections. The role of plasma lipoproteins in atherogenesis is well recognized, but the physiological relevance of their immunoregulatory properties is still questioned. In particular, it is unknown whether hypercholesterolemia should be considered a risk factor for diminished immunity in old age. Methods. To evaluate effects of plasma lipoprotein levels on immune function, we assessed the relation between plasma lipoprotein profiles and NK cell activity. NK cell activity was assayed by release of 51Cr from K562 target cells, and concurrent plasma lipoprotein levels were measured in 47 samples of elderly males (mean age ± SD, 66.6 ± 1.7 years). Results. Univariate regression analyses revealed direct relations between NK cell activity and high-density lipoprotein cholesterol (\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathit{r}\ {=}.46\) \end{document}, \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathit{p}\ {