Intrathymic T cell development and selection proceeds normally in the absence of glucocorticoid receptor signaling

Glucocorticoids are believed to play a role in T cell development and selection, although their precise function is controversial. Glucocorticoid receptor (GR)-deficient mice were used to directly investigate this problem. GR-deficient thymocytes were resistant to dexamethasone-mediated apoptosis, confirming the absence of glucocorticoid responsiveness. An absence of GR signaling had no impact on thymocyte development either in vivo or in vitro. T cell differentiation, including positive selection, was normal as assessed by normal development of CD4+CD8+, alphabetaTCR+CD4+, and alphabetaTCR+CD8+ thymocytes. Negative selection, mediated by the superantigen staphylococcal enterotoxin B (SEB), or anti-CD3/CD28, was also normal in the absence of GR signaling. In contrast to earlier reports, these data demonstrate that GR signaling is not essential for intrathymic T cell development or selection.