Suppression of immune complex vasculitis in rats by prostaglandin.

Immune complex-induced vascular damage can be markedly suppressed by treatment of rats with either prostaglandin (PG)E1 or its stable derivative, 15-(S)-15-methyl PGE1, but not with PGF2 alpha. In addition, PGD2 and PGE2 also show suppressive effects. The PGE1 derivative is considerably more effective than PGE1 and shows potent anti-inflammatory activity even after oral administration. Suppression of the vasculitis reaction is reflected by a greatly diminished increase in vasopermeability, indicating little or no vascular damage. In suppressed animals, the infiltration of neutrophils is greatly reduced, and those leukocytes that have appeared at tissue sites fail to show phagocytic uptake of immune complexes. In suppressed animals, the skin sites nevertheless show deposits of immune complexes and C3 fixation in vascular walls. Neutrophils harvested from the blood of rats treated with PGE1 show depressed responsiveness in chemotaxis and in enzyme secretion after incubation with chemotactic peptide. These studies indicate that certain PG have potent anti-inflammatory activity, which may be related to their effects on leukocytes.