ABSTRACT
Histamine, by far the most important mediator of acute allergic symptoms, and the earliest recognized mediator of the immediate hypersensitivity response, was discovered as a potent vasodilator substance by Dale and Laidlaw in 1910 (1). In 1953 it was associated with tissue mast cells by Riley and West (2). Human mast cells contain 2-5 pg histamine per cell. It is unclear if there are differences in histamine content in different mast cell subsets (Table 1). Rapid advances in molecular biology have led to the discovery of H1-, H2-, and H3-receptors that mediate the complex histamine-induced actions. In this chapter we discuss concepts of the synthesis and metabolism, localization, receptors, effects, and the role of histamine in various syndromes in which basophil and mast cell degranulation occurs.
