Effects of Selenium In Vitro on Human T‐Lymphocyte Functions and K‐562 Tumor Cell Growth

In vitro E‐rosette formation, lymphocyte mitogenesis, and natural killer (NK) cell activity of human blood lymphocytes were strongly inhibited by high concentrations (10 −4 M) of sodium selenite, sodium selenate, and selenium dioxide. Lower concentrations (10 −5 or 10 −7 M) also inhibited E‐rosette formation and natural killer cell activity against K‐562 tumor cells. Lymphocyte transformation induced by concanavalin A (con A) or pokeweed mitogen (PWM) was also inhibited by all selenium compounds tested, but only at the highest concentrations (10 −5 and 10 −4 M). There was depression of the total number of viable lymphocytes following incubation with selenium dioxide only at a high concentration (10 −4 M). Interferon production was enhanced at lower levels (10 −9 to 10 −6 M) of selenium dioxide while a higher concentration (10 −5 and 10 −4 M) appeared to inhibit its production. The mechanism of inhibition by selenium compounds (10 −4 M) is due, in part, to the decrease of viable lymphocytes. It is unclear how other and lower concentrations (10 −7 or 10 −9 M) of selenium compounds inhibit E‐rosette formation, NK activity, or K‐562 tumor cell growth.