Anaphylactic histamine release during inhibition of the proteolytic and kinin-forming system in experimental animals

The experiments were carried out on immunized guinea-pigs. Histamine concentration in the blood and the lung tissue, the plasma prekallikrein and kininogen levels, kininase and fibrinolytic activity were determined. The examinations were made before antigen challenge, during anaphylactic reaction and after pharmacological inhibition of proteolysis. As protease inhibitors--Trasylol and EACA were used. The inhibition of the kinin and fibrinolytic systems by Trasylol and EACA did not markedly affect the allergic symptoms and did not change the high level of blood and lung tissue histamine. These experiments suggest that activation of the kinin system is not essential for the initiation of the immediate response but is the consequence of immunological release of histamine and other mediators.