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Mast cell heterogeneity. Differential synthesis and expression of glycosphingolipids by mouse serosal mast cells as compared to IL-3-dependent bone marrow culture-derived mast cells before or after coculture with 3T3 fibroblasts.

The synthesis and intracellular expression of glycosphingolipids by mouse serosal mast cells (SMC) have been characterized by radiolabeling and TLC and by immunodetection in situ. Chromatographic analysis of purified glycosphingolipids from SMC intrinsically labeled with [14C]galactose and [14C]glucosamine hydrochloride revealed the predominant synthesis of only the simplest neutral glycosphingolipid and ganglioside, glucosylceramide and ganglioside GM3, respectively. Intracellular indirect immunofluorescence staining of permeabilized SMC demonstrated the absence of the more complex neutral glycosphingolipids lactosylceramide, globotriosylceramide, globotetraosylceramide, and globopentaosylceramide, the absence of ganglioside GM1, and the presence of ganglioside GM3. By contrast, permeabilized mouse IL-3-dependent bone marrow culture-derived mast cells (BMMC) and mast cells recovered after 21 days of coculture of BMMC with mouse 3T3 fibroblasts expressed lactosylceramide, globotriosylceramide, globotetraosylceramide, ganglioside GM1, and ganglioside GM3, but not globopentaosylceramide intracellularly as determined by immunofluorescence. The findings indicate a loss of biosynthetic capacity and epitope maintenance for glycosphingolipids with in vivo differentiation of SMC from IL-3-dependent BMMC progenitors. Thus, although mast cells derived after coculture of these progenitors for 21 days with fibroblasts assume multiple SMC-like properties in terms of their histochemical staining and their secretory granule proteoglycan and neutral protease constituents, they do not lose the ability to express complex glycosphingolipids. The finding that glycosphingolipid composition does not change coordinately with other secretory granule markers defines a new stage of mouse mast cell development between the BMMC and SMC and provides evidence that mast cell development is more complex than previously appreciated.

Animals↗

Effects of interleukin-4 or stem cell factor on mast cell mediator release and cytokine gene expression.

We have investigated the capacity of interleukin (IL)-4 or stem cell factor (SCF) to induce direct mediator release from rodent peritoneal mast cells, and also to induce or regulate cytokine gene expression in the human HMC-1 mast cell line. SCF, but not IL-4, induced low levels of serotonin release from mouse or rat peritoneal mast cells; rat mast cells acquired enhanced responsiveness to SCF during culture. IL-4, but not SCF, enhanced ionomycin-induced transcription and secretion of several genes, including the cytokines IL-3, IL-4, granulocyte/macrophage-colony-stimulating factor, IL-8 and the receptor for IL-6 in the human HMC-1 mast cell line.

Animals↗

Mast cells from human gastric mucosa: a comparative study with lung and colonic mast cells.

Mast cells isolated from human gastric mucosa released histamine on challenge with IgE-directed ligands and calcium ionophores but were essentially unresponsive to a variety of non-immunological stimuli. Moreover, immunologically induced histamine secretion from these cells was inhibited by a number of anti-allergic agents including anti-asthmatic chromones, beta-adrenoceptor agonists and phosphodiesterase inhibitors. In total, these data indicate that mast cells from the human gastric mucosa are in many respects functionally similar to their lung and colonic counterparts.

Anti-Inflammatory Agents, Non-Steroidal↗

Mast cells cultured from the peripheral blood of normal donors and patients with mastocytosis originate from a CD34+/Fc epsilon RI- cell population.

Mast cells may be cultured from human peripheral blood in the presence of recombinant human stem cell factor (rhSCF). The characteristics of the cells in peripheral blood that give rise to mast cells are unknown. Because mast cell precursors in human marrow are CD34+, human peripheral blood mononuclear cells from patients with mastocytosis and normal controls were sorted on the basis of CD34 expression and the positive and negative cell populations were cultured in rhSCF, recombinant human interleukin-3 (rhIL-3), or both for 6 weeks. Cell cultures were examined every 2 weeks for total and mast cell number and cell differential using Wright Giemsa and acid toluidine blue stains and antibodies to mast cell tryptase and chymase, cell-associated histamine, and expression of CD34, c-kit, Fc epsilon RI, and Fc gamma RII using flow cytometric analysis. The ultrastructural anatomy of mast cells was examined by electron microscopy. Peripheral blood CD34+ cells cultured in rhSCF with or without rhIL-3 gave rise to cell cultures consisting of greater than 80% mast cells by 6 weeks. CD34+ cells cultured in rhIL-3 alone did not give rise to mast cells, whereas rhIL-3 plus rhSCF increased the final mast cell number eightfold when compared with cells cultured in rhSCF alone. Mast cells increased concomitantly with a decrease in large undifferentiated mononuclear cells. CD34- cells did not give rise to mast cells. Histamine content per cell at 6 weeks was approximately 5 pg. Electron microscopy of 4-week cultures showed immature mast cells containing predominantly tryptase-positive granules that were either homogeneous or contained lattice structures, partial scroll patterns, or central dense cores and mixtures of vesicles, fine granular material, and particles. The CD34+ population at day 0 expressed Kit (65%) and Fc gamma RII (95%), but not Fc epsilon RI, by fluorescence-activated cell sorter analysis. At 6 weeks, CD34+-derived mast cells exhibited Fc epsilon RI in addition to Kit and Fc gamma RII, and were negative for CD34 antigen. Patients with mastocytosis showed a higher number of mast cells per CD34+ cell cultured compared with normal controls. Thus, the mast cell precursor in human peripheral blood is CD34+/Fc epsilon RI- and gives rise to mast cells in the presence of rhSCF with or without rhIL-3, and the number of mast cells arising per CD34+ cell in culture is greater when the CD34+ cells are obtained from patients with mastocytosis compared with normal subjects.

Antigens, CD↗

Histochemical heterogeneity of human mast cells: disease-related differences in mast cell subsets recovered by bronchoalveolar lavage.

Fixation and staining characteristics were studied for mast cells recovered by bronchoalveolar lavage from 67 patients being investigated for lung disease. The number of toluidine blue stained mast cells in formaldehyde-fixed cytocentrifuge preparations was consistently less than in specimens fixed in Carnoy's solution, though the counts were highly dependent on the period of fixation or staining. The cellular histamine content closely correlated with total mast cell numbers in bronchoalveolar lavage fluid, but was not related to the relative proportions of mast cells which were sensitive or resistant to formaldehyde fixation when using a standard protocol. Compared with normal subjects, the numbers of formaldehyde-sensitive mast cells were significantly elevated in patients with bronchial carcinoma, sarcoidosis, extrinsic allergic alveolitis, cryptogenic fibrosing alveolitis, and mycobacterial infection and were particularly high in the cases of interstitial lung disease. An even greater increase in numbers of formaldehyde-resistant mast cells was observed in the patients with sarcoidosis and extrinsic allergic alveolitis. The associations of these mast cell subsets with disease may reflect relationships between the expansion of the formaldehyde-sensitive population and lymphocyte infiltration and between proliferation of formaldehyde-resistant mast cells and tissue fibrosis.

Acetates↗

Fate of bone marrow-derived cultured mast cells after intracutaneous, intraperitoneal, and intravenous transfer into genetically mast cell-deficient W/Wv mice. Evidence that cultured mast cells can give rise to both connective tissue type and mucosal mast cells.

Both connective tissue mast cells and mast cells grown in vitro are derived from multipotential hematopoietic stem cells, but these two mast cell populations exhibit many differences in morphology, biochemistry, and function. We investigated whether the phenotype of cultured mast cells or their progeny was altered when the cells were transferred into different locations in vivo. Cultured mast cells were immature by ultrastructure, and stained with alcian blue but with neither safranin or berberine sulfate, a fluorescent dye that binds to the heparin of connective tissue mast cell granules. By contrast, mast cells recovered from the peritoneal cavity of congenitally mast cell-deficient (WB X C57BL/6)F1-W/Wv (WBB6F1-W/Wv) mice 10 wk after intraperitoneal injection of cultured WBB6F1-+/+ or C57BL/6-bgJ/bgJ mast cells stained with both safranin and berberine sulfate. Staining with berberine sulfate was prevented by treatment of the cells with heparinase but not chondroitinase ABC, suggesting that the adoptively transferred mast cell population had acquired the ability to synthesize and store heparin. Furthermore, the recovered mast cells were indistinguishable by ultrastructure from the normal mature peritoneal mast cells of WBB6F1-+/+ mice, and contained substantially more histamine than mast cells studied directly from culture. Intravenous injection of cultured mast cells resulted in the development of safranin-and berberine sulfate-positive mast cells in the peritoneal cavity, spleen, skin, and glandular stomach muscularis propria. Mast cells also developed on the glandular stomach mucosa, but these cells stained with alcian blue rather than safranin, and did not stain with berberine sulfate. This result suggests that cultured mast cells can give rise to mast cells of either the connective tissue type or mucosal phenotype, depending on anatomical location. Furthermore, transplantation of cultured mast cells into WBB6F1-W/Wv mice had no measurable effect on the anemia of the recipient mice, suggesting a possible strategy for repairing the mast cell deficiency of WBB6F1-W/Wv mice without affecting other bone marrow-derived populations such as erythrocytes. Intravenous injection of representative connective tissue type mast cells (30-50% pure peritoneal mast cells derived from WBB6F1-+/+ mice) gave results similar to those obtained with cultured mast cells: mast cells developing in the peritoneal cavity, skin, spleen, and glandular stomach muscularis propria of WBB6F1-W/Wv recipients stained with safranin and berberine sulfate, whereas mast cells developing in the mucosa of the glandular stomach stained only with alcian blue.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

Low density lipoprotein degradation by rat mast cells. Demonstration of extracellular proteolysis caused by mast cell granules.

The interaction between rat serosal mast cells and low density lipoproteins (LDL) was studied in vitro. When rat 125I-LDL was incubated with mast cells, it was bound to a binding site on the mast cell surface but was not internalized by the cells. Even though 125I-LDL was not internalized, its protein component, apolipoprotein B, was rapidly degraded. The proteolytic activity responsible for the degradation of apolipoprotein B was present in the extracellular fluid of mast cells. It could be shown that the degradation was caused entirely by specific cell organelles of mast cells, the granules, which were spontaneously released into the extracellular fluid during preparation and incubation of the cells. In contrast to uncontrolled spontaneous degranulation, a controlled specific degranulation of mast cells can be induced by treating the cells with the compound 48/80. When increasing amounts of 48/80 were added to mast cell suspensions, a dose-dependent release of granules was observed and an increase in the rate of 125I-LDL degradation resulted. The increase in 125I-LDL degradation closely followed the increase in granule release. Thus, a quantitative relationship between the amount of granules present in the extracellular fluid and the amount of degradation of 125I-LDL could be established. The apolipoprotein part of LDL was extensively degraded by isolated mast cell granules. Analysis by polyacrylamide gel electrophoresis showed that upon incubation of LDL with isolated granules, the apolipoprotein B band rapidly disappeared with simultaneous appearance of several low molecular weight bands. The degradation of 125I-LDL by mast cell granules proceeded optimally at neutral pH and at physiological ionic strength. The results show that mast cell granules are able to efficiently degrade LDL in vitro, once released from mast cells into the extracellular fluid.

Animals↗

Preparation of T cell growth factor free from interferon and factors stimulating hemopoietic cells and mast cells.

A simple two-step method involving ammonium sulfate precipitation followed by hydrophobic chromatography is described for the separation of T cell growth factor (TCGF) from a number of other factors contained in medium conditioned by concanavalin A-stimulated spleen cells. Thus, granulocyte-macrophage colony-stimulating factor, P cell-stimulating activity, pluripotential stem cell-supporting activity and interferon activity were not detected in TCGF partially purified by these steps. T cell-replacing factor co-purified with TCGF. Macrophage activity factor (MAF) co-purified with TCGF, but the ratio of MAF to TCGF activities was reduced more than 20-fold relative to that in crude conditioned medium. All of the factors were present in the 50-80% saturated ammonium sulfate fraction, however, levels of concanavalin A were reduced by 98% in this step. TCGF, separated in this way from these other regulatory factors will be useful in experiments analyzing the actions of TCGF on mixed populations of cells.

Animals↗