Immunological release of histamine from bovine leucocytes. Unusual adrenergic modulation.

Sensitized bovine granulocytes release histamine when exposed to specific antigen. In comparison with in vitro systems in several other species, the modulation of this release by adrenergic agents is unique. Beta-Adrenoceptor stimulation potentiates (rather than inhibits), whereas alpha-adrenoceptor stimulation inhibits (rather than potentiates) histamine release. Adrenaline, which is generally considered to be a physiological antagonist of the anaphylactic reaction, potentiated histamine release in this study. Dopamine, which is present in high concentration in bovine mast cells, was without effect. The results are discussed in terms of the possible role of granulocytes in bovine hypersensitivity.