Release of leukocyte kallikrein mediated by IgE

Abstract

BRADYKININ is a vasoactive nonapeptide believed to mediate various acute inflammatory conditions¹. Although its production in plasma is well defined¹, an understanding of its role in disease is hampered by the lack of information about the mechanism by which it can be generated by an immune process or by any stimulus other than clotting. Immune release of a kinin-generating factor from perfused sensitised guinea pig lung has been reported^2,3. The release is not, however, calcium-dependent and the factor may be a product not of the primary allergic reaction, but of a secondary event⁴. Substantial information is available, however, about the release of other mediators of inflammatory or allergic reactions—histamine, SRS-A, and ECF-A⁵. These are secreted after antigen challenge of basophils and mast cells sensitised with IgE antibody^6–7. The release depends on calcium and temperature, requires energy and is controlled by hormone-receptor interactions which influence the intracellular level of cyclic nucleotides^10–13. We have now demonstrated the immune release of an enzyme from human leukocytes that hydrolyses p-toluene sulphonyl-L-arginine methyl ester (TAMe) and generates bradykinin from citrated human plasma. The release is initiated by the interaction of antigen or anti-IgE with cell-bound IgE^6,14 and seems to be similar in mechanism to the release of histamine and the other mediators of the allergic response.