15-Deoxy-delta 12,14-prostaglandins D2 and J2 are potent activators of human eosinophils

15-Deoxy-Delta(12,14)-PDJ(2) (15d-PGJ(2)) is a degradation product of PGD(2) that has been proposed as an anti-inflammatory compound because of its various inhibitory effects, some of which are mediated by peroxisome proliferator-activated receptor-gamma. In contrast to its reported inhibitory effects on macrophages and other cells, we found that this compound is a potent activator of eosinophils, inducing calcium mobilization, actin polymerization, and CD11b expression. It is selective for eosinophils, having little or no effect on neutrophils or monocytes. 15d-PGJ(2) has an EC(50) of approximately 10 nM, similar to that of its precursor, PGD(2). The concentrations of 15d-PGJ(2) required to activate eosinophils are thus much lower than those required for its anti-inflammatory effects (usually micromolar). 15-Deoxy-Delta(12,14)-prostaglandin D(2) (15d-PGD(2)) is also a potent activator of eosinophils, with an EC(50) about the same as that of PGD(2), whereas Delta(12)-PGJ(2) is slightly less potent. Eosinophils pretreated with PGD(2) no longer respond to 15d-PGJ(2), and vice versa, but in both cases the cells still respond to another eicosanoid proinflammatory mediator, 5-oxo-6,8,11,14-eicosatetraenoic acid. This indicates that the effects of 15d-PGJ(2) are mediated by the DP(2)/chemoattractant receptor-homologous molecule expressed on Th2 cells that has recently been identified in eosinophils. 15d-PGJ(2) is selective for the DP(2) receptor, in that it has no effect on DP(1) receptor-mediated adenylyl cyclase activity in platelets. We conclude that 15d-PGJ(2) and 15d-PGD(2) are selective DP(2) receptor agonists that activate human eosinophils with potencies at least 100 times greater than those for the proposed anti-inflammatory effects of 15d-PGJ(2) on other cells.