ANDROSTENEDIONE METABOLISM BY HUMAN-LYMPHOCYTES

Intact human lymphocytes were incubated with 3H-labeled androstenedione; after extraction and appropriate chromatographic separation, followed by crystallization to constant tritium to carbon-14 ratio to establish radiochemical homogeneity, the following metabolites were identified: testosterone, 5.alpha.-androstane,3,17-dione, 5.alpha.-dihydrotestosterone, androsterone and isoandrosterone. Neither estrogen nor 5.beta.-reduced metabolites were found as products. The major androstenedione metabolizing activities in human lymphocytes were 5.alpha.-reductase and 17.beta.-hydroxysteroid oxidoreductase; in addition, 3.alpha.- and 3.beta.-hydroxysteroid oxidoreductase activities also were present in these cells. The rates of metabolite formation were linear with incubation time up to 4 h, and with cell number up to 2 .times. 107 lymphocytes per ml for the 5.alpha.-reduced products and up to 1.6 .times. 107 lymphocytes per ml for testosterone. In the human, lymphocytes apparently are a potential site of peripheral metabolism of androstenedione to potent androgens.