Human uterine mast cells: Isolation, purification, characterization, ultrastructure, and pharmacology

As part of an ongoing investigation of human mast cell heterogeneity, we have isolated, partially purified and characterized the uterine mast cell and compared it with mast cells isolated from other organs. The average histamine content of myometrium and leiomyofibroma obtained from hysterectomies was 2.1 ± 0.3 (mean ± SEM) μg/g of tissue (n = 10), and the histamine content of the two tissues did not differ significantly. A mild collagenase, hyaluronidase, and DNase digestion was used to disperse the uterine mast cells, with an average yield of 9.5% (range, 0 to 21%). The average histamine/ uterine mast cell was 2.1 ± 0.2 pg (n = 3), and 61 ± 7% (n = 3) of the uterine mast cells survived overnight culture. Early purification efforts with Percoll gradients have yielded up to 80% pure uterine mast cells, with an average of 27 ± 10% (n = 5). Uterine mast cells released histamine in response to the secretogogues anti-IgE and A23187 but did not respond to substance P or to the basophil secretogogues FMLP, C5a, and 12-O-tetradecanoylphorbol-13-acetate. After 1 μg/ml anti-IgE stimulation, the uterine mast cell appeared to make significant quantities of PGD₂ (89 ± 26 ng/10⁶ cells, n = 6) (p < 0.05), as assayed by RIA. Simultaneously, leukotriene C₄ release was 45 ± 15 ng/10⁶ cells, (n = 6) (p < 0.05), as assayed by RIA. Combined gas-chromatography mass spectroscopy analysis of anti-IgE-stimulated cell supernatants confirmed the production of PGD₂. In pharmacologic studies, isobutyl-methylxanthine and isoproterenol blocked anti-IgE-induced histamine release. The uterine mast cell is similar to the lung mast cell in terms of response to secretogogues and release of arachidonic acid metabolites. Ultrastructurally, the uterine mast cell contains scroll granules, crystal granules, combined granules, homogeneously dense granules, and large lipid bodies, many with focal lucencies within them. Particle granules, most frequently present in gut mast cells of mucosal origin, were absent from uterine mast cells. Although certain features are analogous to the ultrastructure of skin or lung mast cells, the combination of structures is distinctive for uterine mast cells.