Prostaglandins and surgical diseases: Part II

Prostaglandins are important in the allograft response. Allograft antigenic stimulation causes release of prostaglandins both in vivo and in vitro. Macrophages and monocytes are the cells that produce the prostaglandins from arachidonic acid via the cyclooxygenase pathway. Prostaglandins exert immunosuppressive effects at several steps on both afferent and efferent phases in the cell-mediated immune system: reduction of Ia expression in antigen-presenting cells, inhibition of IL-1 and IL-2 production, and activation of suppressor cells. The immunosuppressive effects of blood transfusions and essential fatty acids appear to be mediated by PGE.