Uptake of selenium-75 by PHA-stimulated lymphocytes : Effect on glutathione peroxidase

To determine which of a variety of inorganic and organic selenium compounds could best stimulate glutathione peroxidase, human lymphocytes were cultured with a number of selenium sources. The phytohemagglutinin-transformed lymphocytes were cultured in the presence of(75)Se bound to serum proteins (25% v/v) or 10(-7) M concentrations of [(75)Se]-selenite, [(75)Se]-selenate, [(75)Se]-selenocystine, and [(75)Se]-selenomethionine. Organic forms of selenium were taken up in preference to inorganic forms. Control cultures, from which exogenous selenium had been omitted, showed a decreased level of glutathione peroxidase activity at the end of a 4 d culture period. Of the Se sources tested, [(75)Se]-selenocystine and [(75)Se]-labeled fetal calf serum proteins increased enzyme activity significantly, 79 and 47%, respectively, but selenite increased activity only by 7%. These results indicate that selenium from the two organic sources is most readily available for glutathione peroxidase synthesis.