The cancer chemopreventive activity of Se has been suggested to be related to the ability of Se to modulate the immune system, in particular natural killer (NK) cells. To date, studies investigating Se-modulation of NK cell function have used mixed lymphocyte populations or enriched NK cell populations from peripheral blood or spleen. To alleviate extraneous variables, the effects of Se compounds on the NK cytotoxic activity were assessed using a human, non-transformed, NK cell line (NK3.3) derived from a mixed lymphocyte culture from normal donors. Selenite, but not selenomethionine, inhibited the natural cytotoxic and antibody-dependent cytotoxic activity of NK3.3 cells. The data suggest that Se-induced enhancement of NK activity in vivo may not be due to a direct interaction of Se on NK cells. The elevated in vivo NK activity may be explained by an indirect effect of Se (i.e., Se may affect another cell population that in turn releases “factors” that enhance NK cell cytotoxic activity).
- NK cells