Expression of Bcl-x in T cells

The thymus is a major site of apoptosis where programmed cell death is involved in the deletion of self-reactive T cells. We have investigated the role of bcl-x in T cells by defining the expression of its two isoforms, bcl-x and bcl-xs, in a series of human thymocyte cell lines and in human T lymphocytes using the ribonuclease protection assay. Bcl-x1 was the predominant isoform expressed in T cell lines and in T lymphocytes, where expression was further enhanced by PMA/ionomycin. This broad expression supports a central role for bcl-x in thymocyte development perhaps through post-transcriptional regulation.