LIPOPROTEIN-LIPASE EXPRESSION IN NATURAL-KILLER-CELLS AND ITS ROLE INTHEIR CYTOTOXIC ACTIVITY

Lipoprotein lipase (LPL) is the key enzyme in the metabolism of trigly ceride-rich lipoproteins. The patterns of LPL mRNA expression and secr etion of the enzyme have not yet been established in natural killer (N K) cells. We show in the present communication that CD3(-) CD16(+) cel ls (NK cells) transcribe LPL mRNA, express LPL on the surface and secr ete the enzyme. In contrast, there is no LPL expression on the surface of highly purified B and T lymphocytes. Stimulation of NK cells with interleukin-2 (IL-2) reduced the expression of LPL on their surface an d augmented the secretion of LPL by the cells. The addition of anti-LP L antibodies to NK cells in culture led to a complete abrogation of cy totoxicity of NK cells against the K562 tumour cell line. Furthermore, IL-2 stimulation of effector cells reversed the anti-LPL antibody-ind uced inhibition of cytotoxic activity. Overall, these findings suggest that LPL plays a key role in the cytotoxic activity of NK cells.