Prostaglandin B-2 delivers a co-stimulatory signal leading to T cell activation

Most of the data accumulated to date on the immunoregulatory effects of pro staglandins (PG) on T cell activation stem from the archetypal inhibitory e ffect of PGE(2). In this study we provide instead, the first evidence that exogenous PGB(2), a catabolic metabolite of PGE(2), synergizes with signals delivered by T cell receptor (TCR) engagement to induce interleukin-2 (IL- 2) production and IL-2 receptor (IL-2R) alpha-expression in Jurkat cells. A ccordingly, PGB(2) enhances the proliferation of anti-CD3-activated periphe ral blood lymphocytes (PBL), In terms of cellular signaling, we present evi dence that PGB(2) activates tyrosine kinase activities and efficiently incr eases c-fos mRNA expression and nuclear factor-kappa B (NF-kappa B) translo cation to the nucleus. Owing to these features, PGB(2) appears as a new lip id mediator capable of delivering an ancillary signal leading to T lymphocy te activation.