ANALYSIS OF SUSCEPTIBILITY OF MATURE HUMAN T-LYMPHOCYTES TO DEXAMETHASONE-INDUCED APOPTOSIS

We present evidence that dexamethasone (Dex), a synthetic glucocortico steroid, causes apoptosis in mature human T cells, similarly to what h as been reported for murine T lymphocytes. Human T cell clones and sho rt-term activated T lymphocytes treated with Dex show the characterist ic pattern of apoptotic cells, such as hypodiploid nuclei, chromatin c ondensation and DNA fragmentation into oligonucleosomal fragments. How ever, Dex susceptibility of T cells to apoptosis is cell cycle-depende nt. The progression in the proliferative cell cycle (G1 versus S) resc ues Dex-treated T cells from apoptosis. Moreover, occupancy of the T c ell receptor reverses Dex-induced apoptotic phenomena. These observati ons suggest that glucocorticoids contribute to the regulation of the p roliferative or the suicidal response of antigen-activated human T cel ls.