EFFECTS OF SELENIUM STATUS ON BOVINE MONONUCLEAR CELL-FUNCTION

The effects of selenium (Se) status on the distribution and functional capabilities of bovine peripheral blood mononuclear cells (PBMC) were examined. No differences in proliferative responses to mitogens, interleukin (IL)-2 production, IL-2 receptor expression, or lymphocyte trafficking patterns were observed between PBMC from dairy cows maintained on Se adequate or Se deficient diets. In contrast, Se deficiency significantly reduced the numbers of circulating monocytes when compared to cows fed a Se adequate diet. Differences in the number of circulating monocytes had no apparent effect on the accessary functions of these cells with respect to antigen presentation and IL-2 production. These results suggest that the effect of Se-modified diets on bovine defense mechanisms is not mediated by the ability of peripheral blood lymphocytes to respond to antigen and mature into immunocompetent cells.