Influence of iloprost and various prostaglandin derivatives on mouse skin allograft survival, HLA-DR antigen expression and eicosanoid metabolism by human leukocytes.

Treatment of mice bearing allogeneic tail skin grafts with iloprost, a stabilized prostacyclin derivative, as well as dexamethasone prolonged graft survival. Nalador and flunoprost, stabilized prostaglandin E analogues, had similar but weaker effects. The thromboxane agonist U 46619 had no effect on graft rejection. An incubation of human monocytes with iloprost or prostaglandin E2 led to a dose-dependent reduction of HLA-DR antigen expression by these cells. Furthermore, a suppressive effect of these prostaglandin derivatives on the calcium ionophore stimulated release of arachidonic acid metabolites by human polymorphonuclear leukocytes has been shown, which demonstrates an antiinflammatory action of these drugs. Additionally, the eicosanoids were determined in the tail skin after complete allograft rejection. The importance of thromboxane for the rejection of skin grafts has not been confirmed. These data, along with the known antiaggregatory and antiischemic cytoprotective effects of iloprost, suggest that this newly developed drug may be all the more important in clinical organ transplantation.