The role of the mast cell in allergic bronchospasm

In allergic bronchospasm inhaled allergen interacts with specific IgE antibody on the surface of mast cells, inducing the release of mediators, particularly histamine and leukotrienes, which induce bronchoconstriction. Disodium cromoglycate, previously considered to be predominantly a mast cell stabilizing agent, is effective prophylactically in inhibition of early and late phase asthmatic reactions. However, the microenvironment of the airways contains many cell types and the precise role of mast cells is not clear. Lymphocytes, alveolar macrophages, eosinophils, platelets, and neutrophils possess low affinity surface receptors for IgE and can respond to allergen, releasing mediators that have diverse functions. These observations compound the problem of which mediator(s) is most important in pathogenesis of asthma. Moreover, mast cell products modulate the functions of many cells, and thus whether mast cells act directly or indirectly on bronchial smooth muscle requires clarification. Neuropeptides activate or modulate mast cells, and together with evidence of the close association of mast cells and nerves, these observations provide exciting new directions for investigation. Evidence that mast cells from different sites are heterogeneous in their response to stimuli and antiallergic drugs and differ in mediator production and function amplifies the problems identified above. In summary, the role of mast cells in bronchoconstriction is complex and systematic analysis of interactions between mast cells and other cells of the airways is essential.