Mast cell numbers in incisional wounds in rat skin as a function of distance, time and treatment

Chronic heliodermatitis: a morphologic evaluation of chronic actinic dermal damage with emphasis on the role of mast cells

Descriptions of actinically damaged human dermis have focused on the late stages of elastotic degeneration. This has diverted attention from preceding events, which are important for understanding the sequence of pathologic changes that culminate in the deranged fibrous structures of elastotic dermis. We studied specimens from the back of the necks (exposed) and inner arms (unexposed) of 24 individuals, aged 35-84 yr, by light and transmission electron microscopy. Intense sunlight exposure was common to all. A previously undescribed finding was the presence of a perivenular, histiocytic-lymphocytic infiltrate in which numerous mast cells, often in close apposition to fibroblasts, were observed. We have termed this "chronic heliodermatitis." We postulate that mast cell-derived mediators in conjunction with enzymes released by the infiltrating cells lead to breakdown of elastic and collagen fibers.

Mast cells in the initial stages of psoriasis

Mast cells were counted in 122 patients with psoriasis and 80 healthy volunteers, at different times after scratch from 30 min up to 14 days. Koebner's phenomenon was induced in 74% of patients with active disease (63/85) and in 37.5% with stationary psoriasis (6/16). Mast cells were enumerated also in the skin of ten healthy controls, and their number on the inner aspect of the arm was found to range from 16 to 21 (mean, 17.6 +/- 1.65). Scarification increased the number of skin mast cells both in psoriatics and normal controls. The significant difference was noticed from the 4th day on after scratch, reaching a peak at days 14, simultaneously with the appearance of Koebner's phenomenon. In mature psoriatic lesions the number of mast cells was significantly lower than in newly formed psoriatic lesions, and it decreased progressively with effective anthralin treatment. It is concluded that mast cells play a role in skin response to trauma. In contrast to normal wound healing, their number is steadily increasing at the time of formation of the earliest psoriatic lesions.

Hyaluronic acid in bronchoalveolar lavage fluid in patients with sarcoidosis: relationship to lavage mast cells

Hyaluronate (hyaluronic acid), a potential marker for activated pulmonary fibroblasts, appears in increased concentrations in bronchoalveolar lavage fluid from patients with sarcoidosis. The mechanisms underlying fibroblast proliferation are largely unknown but activated alveolar T lymphocytes and macrophages probably play a part; the mast cell is also important for fibroblast proliferation. This study was designed to determine whether there is any association between pulmonary mast cells in lavage fluid, which are known to be increased in patients with sarcoidosis, and signs of pulmonary fibroblast activation. A strong correlation was found between lavage fluid hyaluronate and recovered mast cells (r = 0.72, p less than 0.001). Moreover, mast cell and hyaluronate estimations correlated inversely with lung volume and transfer factor for carbon monoxide, and both indices increased with advancing radiological sarcoid stage. Macrophage and granulocyte counts were normal in lavage fluid from patients with sarcoidosis and were not related to lavage fluid hyaluronate or laboratory signs of the disease in the lungs. Lymphocytes were recovered in increased numbers (p less than 0.001) and were related to the lavage fluid mast cells and hyaluronate. It is concluded that in sarcoidosis release of hyaluronate into the airways is related to the degree of lung disease and to the local inflammatory reaction in the lung as defined by increased numbers of mast cells and lymphocytes in lavage fluid. The findings may reflect a link between the immune system, activation of mast cells, and a pulmonary fibroblast proliferation.

Ultrastructure of mast cells in the hyperplastic buccal mucosa of the zinc-deficient rat

As previously reported, young rats on zinc-deficient diets develop a marked epithelial hyperplasia in the mucosa of the cheek, associated with a four-fold increase in the number of mast cells in the lamina propria. We now report the results of a quantitative and qualitative ultrastructural study of these mast cells. In contrast to the cells in mast cell-related disease, the cells were of normal morphology, but of consistently increased size, containing proportionally increased numbers of mitochondria and specific granules. The size distribution of the granules was as in controls. Microvilli were lengthened in proportion to the increase in the cell circumference. The number of nuclear pores was increased but their spacing was as in controls. In all these measurements, the experimental mast cells were a remarkably homogeneous population. We conclude that mast cells are capable of developing into cells of larger size showing evidence of greater activity. It may be that this development occurs in response to the same (unknown) stimulus which causes their number to increase. By virtue of their increased number and size, mast cells may play an important role in the enhancement of the microcirculation commonly seen in conditions of epithelial hyperplasia.