Role of tumor necrosis factor-alpha and glucocorticoid on lipopolysaccharide (LPS)-induced apoptosis of thymocytes.

Administration of bacterial lipopolysaccharide (LPS) into mice markedly induced the apoptosis of CD4+8+ thymocytes. The injection of anti-tumor necrosis factor (TNF)-alpha antibody or RU38486, a glucocorticoid receptor antagonist, into mice definitely inhibited LPS-induced apoptosis of thymocytes. Addition of the sera 1 h after injection of LPS into in vitro cultures of thymocytes caused thymocyte apoptosis. It was also prevented by either anti-TNF-alpha antibody or RU38486. Further, recombinant TNF-alpha and hydrocortisone collaborated in induction of the thymocyte apoptosis in vitro. The in vivo phenomenon of LPS-induced apoptosis of thymocytes was reproducible by the in vitro experimental system. It was therefore suggested that both TNF-alpha and glucocorticoid participate and collaborate as effector molecules in LPS-induced apoptosis of thymocytes.