The effects of dietary selenium on the immune system in healthy men

Eleven men were fed foods naturally high or low in selenium for 120 d. Sele nium intake was stabilized at 47 mug/d for 21 d, then changed to either 13 or 297 mug/d for 99 d, leading to significantly different blood selenium an d glutathione peroxidase concentrations. Serum immunoglobulins, complement components, and primary antibody responses to influenza vaccine were unchan ged. Antibody titers against diphtheria vaccine were 2.5-fold greater after reinoculation in the high selenium group. White blood cell counts decrease d in the high-selenium group and increased in the low-selenium group, resul ting primarily from changes in granulocytes. Apparent increases in cytotoxi c T-lymphocytes and activated T-cells in the high-selenium group only appro ached statistical significance. Lymphocyte counts increased on d 45 in the high-selenium group. In vitro proliferation of peripheral lymphocytes in au tologous serum in response to pokeweed mitogen was stimulated in the high-s elenium group by d 45 and remained elevated throughout the study, whereas p roliferation in the low selenium group did not increase until d 100. This s tudy indicates that the immune-enhancing properties of selenium in humans a re the result, at least in part, of improved activation and proliferation o f B-lymphocytes and perhaps enhanced T-cell function.