TCR-mediated death of mature T lymphocytes occurs in the absence of p53.

The p53 protein plays an important role in various forms of thymocyte apoptosis, however its role in mature T lymphocyte death caused by TCR stimulation has not been examined. We demonstrate here that T cell blasts derived from mice containing a germ-line deficiency of the p53 tumor suppressor gene are susceptible to TCR-induced apoptosis to the same degree as wild-type T cells. TCR stimulation of both resting and proliferatingT cells results in up-regulated expression of the p53-induced genes Bax and p21, and the induction of these genes appears reduced in T cells that are deficient in p53. Thus, while activation of p53-dependent genes following TCR stimulation is defective in p53-/- T cells, there is no impairment in their ability to undergo apoptosis. These results suggest that TCR-mediated apoptosis of mature T cells takes place via a pathway that is independent of p53.