Mast Cell Subpopulations Research Articles

Effector cell heterogeneity in immediate hypersensitivity reactions.

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)

The distribution of Helix pomatia lectin receptors on mouse lymphoid cells and other tissues.

The distribution of receptors for the Helix pomatia lectin on mouse lymphoid cells and other tissues was investigated. Using a sensitive rosetting assay combined with immunofluorescence, lectin receptors were found on the membrane of approximately 90% of peripheral T lymphocytes, 75% of thymocytes, 30% of bone marrow cells, 20% of nude spleen cells, 15-50% of peritoneal exudate macrophages, and a subpopulation of peritoneal exudate mast cells. The Thy-1-positive nude spleen cells were predominantly Helix lectin receptor-negative. Approximately 5% of B lymphocytes were weakly positive, and neutrophils were negative. Receptors were present also on a subpopulation of cells of a fibroblast cell line and in acetone powder from the liver and, at a lower level, from the kidney and brain. Membrane receptors on all cell types were partially detectable without neuraminidase treatment of the cells. Two methods of fractionating Helix lextin-positive cells were employed, which gave significantly different results. By rosetting and depletion using density fractionation, T cell mitogen responses were abolished, while B cell mitogen responses, T cell cytotoxicity, and natural killer cytotoxicity were only slightly affected, if at all, Helix lectin-agarose column fractionation seemed more sensitive, in that essentially all natural kill cells bound to the column, as well as considerable number of B lymphocytes. Cytotoxic T cells were heterogeneous; roughly half were not bound, but the remainder were bound and eluted.

Heterogeneity of bronchial lumen mast cells which are homogeneous by electron microscopy

Bronchial lumen mast cells were obtained by bronchial lavage from rhesus monkeys and fractionated on a discontinuous metrizamide gradient. Those cells identified as pleomorphic by standard microscopy sedimented in the higher concentrations of metrizamide, while the round cells were dispersed through all gradient fractions. Electron microscopic studies of the pleomorphic and round cells demonstrated that these were morphologically identifiable as mast cells. Although all the cells appear to be mast cells, they are heterogenous in that mast cells in the higher concentrations of metrizamide had higher concentrations of histamine. By contrast, the mast cells in the lower concentrations of metrizamide had greater biologic activity as indicated by greater release of histamine following an immunologic stimulus. The heterogeneity of bronchial lumen mast cells shown by light microscopy, histamine content, and histamine releasibility may be due to the presence of subpopulations of mast cells or changes in a single cell line reflecting differential maturation.