Induction of Apoptosis in Thymocytes by Prostaglandin E₂ In Vivo

Abstract

In vivo administration in mice of a synthetic analog of prostaglandin E₂ (PGE₂) caused a selective and dramatic decrease of CD4⁺CD8⁺ double-positive, CD3/T-cell-receptor-αb¹⁰ cells in the thymus. This loss was corticosteroid-independent and not affected by Cyclosporin A. The disappearance of CD4⁺CD8⁺ thymocytes was strictly correlated with the induction of apoptosis inside the thymus as shown by morphological studies and by the induction of intracellular transglutaminase expression. Considering that PGE₂ has been found to be produced by different cell populations inside the thymus, these results indicate that PGE₂ may act as endogenous signals for apoptosis during T-cell differentiation.