The role of polymorphonuclear leukocytes in delayed hypersensitivity skin reactions: suppressive effects of anti-polymorphonuclear leukocyte serum.

Rabbit antisera (APS) against normal guinea pig peritoneal exudate polymorphonuclear leukocytes (PMN), when injected intraperitoneally three times within 24 h into guinea pigs, lead to a marked fall in the blood PMN count (below 100/mm3) 24-72 h after the injection and a mild depression in the number of circulating mononuclear leukocytes (MNC) at 36-72 h. APS treatment of guinea pigs led to a marked suppression of delayed hypersensitivity skin reactions in response to dinitrophenylated bovine gamma-globulin. The volume, induration, mean diameter of the reaction and leukocyte (both PMN and MNC) emigration into local sites were suppressed, as was, to a lesser extent, vascular permeability. Based on these observations it appears that circulating PMN are required for the full expression of delayed hypersensitivity reaction engendered by bovine gamma-globulin.