Human mast cells and basophils--structure, function, pharmacology, and biochemistry.

This review will focus on the structure and function of human mast cells and basophils and on the biochemistry and regulation of their activity by pharmacologic agents. In the last two years or so, techniques have been developed in this laboratory 1'2 for the purification of these cells. It has become possible, therefore, to characterize the pharmacologic and biochemical profiles of the purified human mast cells and basophils. These studies are in a very early stage, however, and much work remains to be done. As a result, this review will include information that has been obtained from studies of non-human mast cells, where such studies provide information which has not yet been corroborated in the human systems. Basophils account for less than 1% of the circulating leukocytes in the blood and appear to be descendents of the promyelocytic series in bone marrow. Mast cells, on the other hand, tissue bound cells generally found in the vicinity of small blood vessels and the lymphatic draining system, may be derived either from bone marrow, thymus, or undifferentiated mesenchymal cells. Both cell types are highly granulated, excitable cells which, when exposed to appropriate stimuli, degranulate and release granule-contained mediators such as are listed in Table 1. Mediators released by mast cells and basophils are divided into two types: preformed mediators such as histamine, inflammatory proteases, neutrophil chemotactic factor, and heparin, and newly synthesized mediators such as the metabolites of arachidonic acid, PAF (acetylglycerylether phosphorylcholine-AGEPC), and others. Mast cells appear to generate quantities of arachidonic acid metabolites that are at least an order of mag