Effect of an Antihistamine on the Increased Vascular Permeability induced by Leucocyte Lysosome Fractions

Abstract

IN previous publications ^1–3 I reported the production of immediate increases in vascular permeability in rat tissues treated with a basic protein fraction extracted from lysosomes of exudate polymorphonuclear (PMN) leucocytes. It was suggested that the permeability effect was caused by the release of vasotropic amines from tissue mast cells by a component of the lysosomes^2,4. Part of the evidence cited in support of this mechanism was the significant inhibition of tissue reaction to the extract after treatment of rats with an antihistamine drug. This observation, however, was made in animals treated with a large dose of the antihistamine, and no consideration was given to non-specific effects of such a dose on vascular response to generalized inflammatory stimuli. Additional experiments with appropriate controls for non-specific effects of the antihistamine have now been performed. This communication reports results which confirm our earlier conclusion.