Immunologic release of histamine from bovine polymorphonuclear leukocytes.

Blood from calves sensitized to horse serum was fractionated to yield a suspension containing 94% granulocytes. These cells released up to 90% of their total histamine when exposed to the antigen. This is a noncytotoxic reaction similar to that observed in human beings, rabbits, and guinea pigs. Higher concentrations of antigen caused inhibition of histamine release. This immunologic reaction may be important in bovine hypersensitivity, especially in the lungs, where intravascular aggregations of granulocytes are found at the height of the anaphylactic response.