Effector cell heterogeneity in immediate hypersensitivity reactions

Abstract

Histologic heterogeneity in the basophil and mast cell populations has been apparent for many years. The advent of tissue culture and cell separation procedures has now made it possible to explore distinct populations of basophils and mast cells, as should be evident from this review. In fact, the logical extension of such technology is the requirement that cell preparations used in exploring basophil and mast cell function be carefully defined to permit comparison of data from one laboratory to another. While this is a practical application of the knowledge of the characteristics of heterogeneity, the implications for future developments in the understanding of basophil and mast cell function are more theoretical. While both basophils and mast cells respond to degranulating stimuli and antiallergic compounds in a similar fashion, as a rule, this review has noted several exceptions including the failure of disodium cromoglycate to prevent rat mucosal mast cell degranulation induced by immunologic stimuli. Such observations suggest that the ability of given drugs to inhibit allergic responses in one target organ and not in another may be due in part to differing mast cell responses. This hypothesis can be extended to variation in response among infants, children, and adults to such drugs as antihistamines. Furthermore, the variety of symptoms seen in individuals may be a reflection of differing responses of those individuals' mast cells from organ to organ. For instance, one subject with ragweed sensitivity might express this sensitivity as asthma, and a second subject with ragweed sensitivity might express this sensitivity as rhinitis. This would depend upon the ability of their pulmonary and upper airway mast cells to bind ragweed-specific IgE, degranulate to IgE-mediated stimuli, or to be regulated by intrinsic control mechanisms. Of a yet more speculative nature is the attempt to discern the basis for basophil, and particularly mast cell, heterogeneity. The function of the mast cell is unknown, but theories include the rejection of parasites; regulation and repair of connective tissue; regulation of the microvasculature; regulation of gastric acid secretion; limitation of delayed hypersensitivity reactions; and detoxification of surrounding tissues. Any or all of these theories may be correct, however, such a diversity of possible biologic roles for the mast cell suggests that mast cell subpopulations may have highly specialized functions reflected in stimuli that lead to their proliferation, their response to degranulating stimuli, and their mediator content.(ABSTRACT TRUNCATED AT 400 WORDS)