Histochemical studies on mast cells in cattle skin

Synopsis Cells in the skin of cattle which gave a green fluorescence after formaldehyde treatment could be stained orange with Acridine Orange and blue with Astrablau. It is concluded that these cells are mast cells containing heparin and a catecholamine, probably dopamine.     

Atrazine-induced degranulation of thyroid mast cells in peripubertal and adult rats

Atrazine is a commonly used pesticide in the US and the non-EU countries. It is classified as an endocrine-disrupting chemical and is well-known for its reproductive toxicity in mammals and lower vertebrates. The study on atrazine effects on thyroid mast cells was performed on juvenile/peripubertal and adult male Wistar rats orally gavaged with atrazine at doses of 50 mg/kg of body weight (bw) or 200 mg/kg bw. In order to visualize the mast cell population within the thyroid gland, a histochemical staining method of toluidine blue was used. The results of the histological evaluation demonstrated a prominent increase in mast cell degranulation in both age groups and at both atrazine doses. According to the stereological analysis, a statistically significant decrease in the mast cell volume density in the young rats exposed to a higher dose of atrazine was found when compared to the corresponding control. The numerical density of mast cells significantly decreased in a higher-dose atrazine treated adults in comparison to the control. The obtained data suggest that atrazine-affected mast cells would probably have a consequent influence on thyroid follicular cells and/or thyroid microvasculature via paracrine action of released mediators, but might also be involved in already suggested thyroid cancerogenesis.     

Precursor of mast cells fixed in the skin of mice

The presence and origin of mast-cell precursors fixed in the skin tissue of mice were investigated. Giant granules of beige (C57BL/6-bg^j/bg^j, Chediak-Higashi syndrome) mice were used to distinguish different populations of mast cells. Pieces of the skin were grafted from the intact WBB6F¹ (WB × C57BL/6)F¹?+/+ mice onto the back of the WBB6F¹?+/+ mice which had been irradiated and injected with bone marrow cells of C57BL/6-bg^j/bj^j mice (bg^j/bg^j ?+/+ chimeras). Although the number of mast cells in the skin grafts decreased after the transplantation, the mast-cell precursors circulating in the bloodstream of bg^j/bg^j ?+/+ chimeras (bg^j/bg^j type) did not seem to enter into the skin grafts, because most of mast cells were of +/+ type after the recovery of mast-cell number to pregrafting levels. As a considerable proportion of +/+-type mast cells was labeled with ³H-thymidine, the recovery of mast-cell number in the grafts was attributed to the proliferation and differentiation of +/+-type precursor cells fixed in the skin tissue of the donor. On the other hand, the skin of WBB6F¹-W/W^v mice seemed to be depleted of fixed precursors, because most of mast cells were of bg^j/bg^j type in skin grafted from WBB6F¹-W/W^v mice to bg^j/bg^j?+/+ chimeras. Since the fixed precursor cells which proliferate and differentiate into mast cells after skin grafting may be transferred to WBB6F¹-W/W^v mice by bone marrow transplantation, such precursor cells seem to have been derived from the bone marrow.     

Action of lysosomotropic modulators on the thyroid cells of rats

Hydrocortisone, ammonium chloride, pepstatin and contrykal have been studied for their effect on incubated and cultured fragments of rat thyroid gland. It is found that the radioactive iodine uptake by thyroid gland cells is inhibited by hydrocortisone, ammonium chloride and pepstatin. Pepstatin induces formation of vacuoles with nonhydrolyzed thyroglobulin in thyrocytes.     

Circadian rhythm of the thyroid mast cells in untreated and methylthiouracil-treated rats

Recent investigation have shown that mast cells of the rat thyroid participate in the regulation of thyroid function. Serotonin released from the mast cells influenced by thyrotropin promotes iodothyronine secretion by its effect on the thyroid follicle cells. The present histophysiological studies on the circadian rhythm in the normal rat thyroid reveal a close correlation between the number of the thyroid mast cells and the thyroid function. It has been shown that in the morning, when thyroid function is decreased, the number of the mast cells is low, but at noon it shows an increase an then is highest in the evening, when the thyroid activity is most intense. This phenomenon suggests a relationship between the mast cell function and the thyroid feedback mechanism. In methylthiouracil-treated rats inhibition of the thyroid iodothyronine production and change of the feedback mechanism function induce development of a hypertrophic goitre in which degranulation of the mast cells accompanied by release of their bioamines induce dilatation of blood vessels and increase in the thyroid blood flow. Simultaneously the circadian rhythm of the thyroid mast cell occurrence is changed, i.e. their number found in the morning gradually decreases by the evening.     

Vitamin A and the biosynthesis of sulphated mucopolysaccharides. Experiments with rats and cultured neoplastic mast cells

1. The uptake and incorporation of [(35)S]sulphate into mucopolysaccharides by colon and duodenum in vitro are unaffected by the vitamin A status of the animals. 2. Uptake and incorporation in vivo are unaffected at 4hr. after injection of [(35)S]sulphate, but at later times are decreased in some tissues of vitamin A-deficient animals. 3. The rate of removal of (35)S from blood, its rate of appearance in urine, the plasma concentration of sulphate and the uronic acid content of several tissues are not significantly altered in vitamin A deficiency. 4. These results, and direct measurement of (35)S in mucopolysaccharides at various times after injection of [(35)S]sulphate, suggest that the synthesis of mucopolysaccharides is unaffected but that their turnover is increased in vitamin A deficiency. 5. Neither the growth rate of, nor the incorporation of [(35)S]sulphate into heparin by, P815Y and HC cultured neoplastic mast cells is decreased when the horse serum necessary for growth is treated with ultraviolet light or is replaced by serum from vitamin A-deficient rats. 6. The addition of citral is no more toxic to growth rate or to incorporation of (35)S than is the addition of vitamin A itself. 7. It is concluded that neoplastic mast cells in culture do not require vitamin A for growth or for the synthesis of heparin. 8. None of these results is compatible with the view that vitamin A or a derivative is directly involved in the biosynthesis of sulphated mucopolysaccharides.     

Purification and characterization of human skin mast cells. Evidence for human mast cell heterogeneity

Our previous studies of human lung and intestinal mast cells failed to show the heterogeneity found among mast cells in murine species. Recently, we and others have developed techniques for the enzymatic dispersion of human neonatal skin mast cells. In addition, we are now able to make single cell suspensions of mast cells from adult skin and to purify these cells to near homogeneity. Comparative studies of mast cells from these several sources have uncovered several major differences among them. Adult and neonatal skin mast cells themselves differ in that the former are 10-fold less sensitive to goat anti-human IgE, with maximal release occurring at 3.0 and 0.3 microgram/ml, respectively. Skin mast cells also differ in optimal temperature for release: adult mast cells respond maximally at 23 to 30 degrees C and neonatal cells at 37 degrees C. Skin mast cells from both sources are dramatically different from lung and intestinal mast cells in two aspects. First, skin mast cells are quite responsive to several stimuli--morphine sulfate (10(-4) to 10(-6) M), substance P (10(-5) to 10(-7) M), compound 48/80 (10 to 0.1 microgram/ml), f-Met peptide (10(-6) M), and C5a (10(-8) M)--to which the other mast cells fail to respond. Second, although stimulated skin mast cells produce prostaglandin D2, little leikotriene C4, if any, is generated, unlike lung or intestinal mast cells. These differences in inflammatory potential among human mast cells from various sites have important implications for the management of allergic and inflammatory responses.