Immunomodulative effects of aflatoxins and selenium on human natural killer cells.

The possible immunomodulative effects of aflatoxin B1 and selenium (as sodium selenite) at concentrations lower than 5.10(-11) M or 0.05ppb and 10(-5) M, respectively on natural killer (NK) cells from healthy volunteers were evaluated by a 51Cr release natural killer assay. Aflatoxin B1 and selenium separately had an immunosuppressive effect on NK cell activity. When they were studied in combination, they caused a statistically significant increase of the cytotoxic activity of NK cells in the presence of the lowest concentrations of aflatoxin B1 (0.005ppb) and of sodium selenite (10(-8)M).