Functional testosterone receptors in plasma membranes of T cells

T cells are considered to be unresponsive to testosterone due to the absence of androgen receptors (AR). Here, we demonstrate the testosterone responsiveness of murine splenic T cells in vitro as well as the presence of unconventional cell surface receptors for testosterone and classical intracellular AR. Binding sites for testosterone on the surface of both CD4 + and CD8 + subsets of T cells are directly revealed with the impeded ligand testosterone‐BSA‐FITC by confocal laser scanning microscopy (CLSM) and flow cytometry, respectively. Binding of the plasma membrane impermeable testosterone‐BSA conjugate induces a rapid rise (<5s) in[Ca 2+ ] i of Fura‐2‐loaded T cells. This rise reflects influx of extracellular Ca 2+ through non‐voltage‐gated and Ni 2+ ‐blockable Ca 2+ channels of the plasma membrane. The testosterone‐BSA‐induced Ca 2+ import is not affected by cyproterone, a blocker of the AR. In addition, AR are not detectable on the surface of intact T cells when using anti‐AR antibodies directed against the amino and carboxy terminus of the AR, although T cells contain AR, as revealed by reverse transcription‐polymerase chain reactions and Western blotting. AR can be visualized with the anti‐AR antibodies in the cytoplasm of permeabilized T cells by using CLSM, though AR are not detectable in cytosol fractions when using the charcoal binding assay with 3 H‐R1881 as ligand. Cytoplasmic AR do not translocate to the nucleus of T cells in the presence of testosterone, in contrast to cytoplasmic AR in human cancer LNCaP cells. These findings suggest that the classical AR present in splenic T cells are not active in the genomic pathway. By contrast, the cell surface receptors for testosterone are in a functionally active state, enabling T cells a nongenomic response to testosterone.—Benten, W. P. M., Lieberherr, M., Giese, G., Wrehlke, C., Stamm, O., Sekeris, C. E., Mossmann, H., Wunderlich, F. Functional testosterone receptors in plasma membranes of T cells. FASEB J. 13, 123–133 (1999)