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PubMed2002

Mast cells induce upregulation of P-selectin and intercellular adhesion molecule 1 on carotid endothelial cells in a new in vitro model of mast cell to endothelial cell communication.

It is suggested that mast cells contribute to cell recruitment in inflammation through the upregulation of endothelial adhesion molecules. P-selectin and intercellular adhesion molecule(ICAM)-1 are two key adhesion molecules that have been associated indirectly with mast cell activity. The canine C2 mastocytoma cell line and primary cultures of canine carotid endothelial cells were used to establish a new in vitro model to help study the interaction between mast cells and endothelial cells. Carotid endothelial cells were incubated with mast cell mediators to uncover their effect on endothelial ICAM-1 and P-selectin expression. To assess the relative contributions of tumour necrosis factor (TNF)-alpha and histamine to such effect, an H1 antihistamine and a TNF-alpha blocking antibody were used. Prior to activation by mast cell mediators, P-selectin was expressed only within the cytoplasm, and ICAM-1 was constitutively expressed on the surface of the canine carotid endothelial cells. Both adhesion molecules were enhanced significantly and strongly upon mast cell activation at various time points. Unstored TNF-alpha was fully responsible for ICAM-1 upregulation. P-selectin was up-regulated by both preformed and newly synthesized mast cell mediators, but neither histamine nor TNF-alpha accounted for such an effect. Therefore,a new model is proposed in which the pro-inflammatory effect of mast cells on endothelial cells can be studied in vitro. In this model, it has been demonstrated that only TNF-alpha accounts for the overexpression of ICAM-1 induced by mast cells, and that mast cells up-regulate P-selectin expression through a histamine-independent mechanism.

Animals↗
PubMed1997

Mast cells and atopic dermatitis. Stereological quantification of mast cells in atopic dermatitis and normal human skin.

Stereological quantification of mast cell numbers was applied to sections of punch biopsies from lesional and nonlesional skin of atopic dermatitis patients and skin of healthy volunteers. We also investigated whether the method of staining and/or the fixative influenced the results of the determination of the mast cell profile numbers. The punch biopsies were taken from the same four locations in both atopic dermatitis patients and normal individuals. The locations were the scalp, neck and flexure of the elbow (lesional skin), and nates (nonlesional skin). Clinical scoring was carried out at the site of each biopsy. After fixation and plastic embedding, the biopsies were cut into 2 microns serial sections. Ten sections, 30 microns apart, from each biopsy were examined and stained alternately with either toluidine blue or Giemsa stain and mast cell profile numbers were determined. The study yielded the following results: (1) in atopic dermatitis lesional skin an increased number of mast cell profiles was found as compared with nonlesional skin, (2) comparing atopic dermatitis skin with normal skin, a significantly increased number of mast cell profiles per millimetre squared was found in specimens from the neck, (3) staining with toluidine blue yielded a lower number of mast cell profiles than Giemsa staining, (4) the use of Carnoy's fixative resulted in a lower mast cell profile count than the use of formaldehyde, and (5) there was no statistically significant correlation between the clinical score and the number of mast cell profiles per millimetre squared. Using stereological techniques, this study indicated that mast cells might participate in the inflammatory process in skin leading to atopic dermatitis.

Adult↗
PubMed2003

Indolent systemic mast cell disease: immunophenotypic characterization of bone marrow mast cells by flow cytometry.

BACKGROUND: Mast cell disease has a low prevalence and is difficult to diagnose in the absence of the characteristic skin lesions that usually accompany the condition. Extracutaneous involvement is not easy to assess. There are reports in the recent literature on the use of tryptase as a reliable immunohistochemical marker as well as on the study of the immunophenotype of bone marrow mast cells. The latter is of great help for the diagnosis of systemic involvement as, after the skin, the bone marrow is the organ most commonly affected by the disease. OBJECTIVE: We describe two cases of indolent systemic mast cell disease (SMCD) where flow cytometry was used to identify immunophenotypical characteristics of bone marrow mast cells. Recent advances in the application of this technique prove it can be a good diagnostic tool for assessing systemic involvement of the disease. PATIENTS AND METHODS: Two adult subjects with indolent SMCD had multiple clinical symptoms. Cutaneous lesions were the clue to the diagnosis but, subsequently, in the presence of disturbing symptoms, involvement of other organ systems was confirmed. In both cases, the authors used flow cytometry techniques, as described by Escribano et al. (1998) to define the immunophenotype of bone marrow mast cells. RESULTS: Both patients were diagnosed with indolent SMCD with cutaneous and bone marrow involvement. Also, they presented visible clues to the presumptive bone, cardiovascular and nervous system involvement. Gastrointestinal manifestations were documented in one case. CONCLUSIONS: The use of flow cytometry on bone marrow samples from patients with mastocytosis reveals immunophenotypic differences that can serve to allow classification of these subjects in the category of indolent SMCD even though involvement of another organ system may not be thoroughly confirmed.

Aged↗
PubMed1992

Histamine secretion from human mesenteric and adenoidal mast cells.

Human mast cells were obtained from adenoids and mesentery by enzymatic dispersion of the tissues with the enzyme collagenase. The digestion of the tissues resulted in a cell suspension which contained 1-2% mast cells. 37.3% (adenoids) and 33.4% (mesentery) of total histamine initially present in the tissues was recovered in the dispersed cell suspensions. More than 90% of the cells were viable. The adenoidal mast cells could be sensitized passively in vitro with homologous reaginic serum and released histamine after challenge with specific antigen. Both populations of mast cells were sensitive to the action of anti-human IgE; the reversed anaphylaxis with anti-IgE was higher in mesenteric mast cells. Both examined mast cell populations were sensitive to the challenge with polymyxin B, concanavalin A and ionophore A23187, however, histamine release was only up to 10% and 20% for adenoidal and mesenteric cells, respectively. Only mesenteric mast cells responded to the action of compound 48/80. Histamine release, induced by polymyxin B, was rapid (maximal release within 5 min), maximal in the presence of 3 mM extracellular calcium ions (but also occurred in the absence of the cation).

Adenoids↗
PubMed1992

The c-kit receptor ligand functions as a mast cell chemoattractant.

Mast cells accumulate at sites of neovascularization, solid tumors, and many immune reactions. Such accumulation requires directed migration of mature mast cells or their precursors. The nature of the chemoattractants that regulate mast cell motility and the identity of the receptors that mediate the chemotactic response are poorly understood. We have tested the ability of stem cell factor (SCF), a mast cell growth factor, to stimulate mast cell migration. Our results show that SCF is a potent mast cell attractant that stimulates directional motility of both mucosal and connective tissue-type mast cells. The activity is potentiated by costimulation with interleukin-3 (IL-3), another mast cell chemoattractant. SCF, a known ligand for the c-kit tyrosine kinase receptor, was unable to stimulate motility in W42 mutant mast cells, which have a defective c-kit tyrosine kinase. However, W42 mast cells were still able to migrate in response to IL-3. These results show that SCF is a chemotactic factor as well as a growth factor and that the c-kit receptor can transduce signals leading to both cell proliferation and increased directional cell motility.

Animals↗
PubMed1983

Mast cells and asthma. The role of mast cell mediators in the pathogenesis of allergic asthma.

Upon a specific allergic reaction mediators released from mast cells found free in the bronchial lumen or in the epithelial surface loosen the interepithelial cell tight-junctions allowing the entrance of more allergen to deeper mast cells. The primary and secondary mediators thereby generated induce further increased vascular permeability which leads to the entrance of plasma proteins and platelets. The other immediate responses induced by mediator release are smooth muscle constriction, mucus secretion and leukocyte chemoattraction. Vagal afferent and reflex efferent stimulation are induced by histamine and probably other mediators which might contribute both to the bronchospasm as well as mucous gland secretion. Subacute responses include increased cellular infiltrates, mucosal edema, desquamation, basement membrane thickening, goblet cell hyperplasia and mucus secretion. These responses may occur because of the continued release of primary and secondary mediators as well as effects caused by the mast cell granule matrix-derived factors. It can thus be seen that many of the pathologic features of asthma may be attributed to mast cell degranulation.

Airway Obstruction↗
PubMed1997

Subcapsular cell hyperplasia and mast cell infiltration in the adrenal cortex of mice: comparative study in 7 inbred strains.

Subcapsular cell hyperplasia (SCH) in the adrenal cortex of aged mice (13-15 months old) was frequent in both sexes of BALB/c, C3H/He, DBA/2J and IQI/Jic mice and in the females of A/J and C57BL/6, although the incidence and severity of SCH were considerably different among mouse strains. Mast cells were closely associated with SCH in the A/J, BALB/c, C57BL/6, DBA/2J and IQI/Jic mice, but not in the C3H/He strain. Compared with other strains, IQI/Jic mice had a significantly larger number of mast cells in the adrenal glands. Our findings suggest that mast cells may participate in the development of SCH, and IQI/Jic would be suitable for studying the pathogenesis of SCH and the role of mast cells in this lesion.

Adrenal Cortex Diseases↗
PubMed1997

The equine endometrial mast cell during the puerperal period: evaluation of mast cell numbers and types in comparison to other inflammatory changes.

Endometrial biopsies of 44 broodmares were histologically examined on days 3, 6, and 9 postpartum. The mares were subdivided into three groups according to the course of the puerperal period. In 29 mares, parturition and expulsion of the placenta was normal, six mares showed dystocia, and in nine mares, the placenta was retained for > 2 hours. Tissue samples were evaluated histologically, and the average numbers of granulocytes, lymphocytes, macrophages, siderophages, and mast cells was determined. Protease content of mast cells was examined with a double-enzyme immunohistochemical staining technique, using a histochemical reaction for chloroacetate esterase and fast blue to detect chymase activity and an immunohistochemical staining method with a polyclonal antibody and fast red for the detection of tryptase. Analyzing the cell numbers using the statistical software Statistica, a marked inflammatory reaction was observed in the endometrium postpartum. Although the number of granulocytes decreased during the first 9 days postpartum, the number of lymphocytes, macrophages, and siderophages increased. No significant difference in the number of any of these cell types could be demonstrated in the three different courses of the puerperal period, although the numbers of these cells seemed to be lower in mares with dystocia. In contrast with other cells, no change in the number of endometrial mast cells was observed during the puerperal period, but a significantly lower number were found in the endometrium of mares with retained placenta. The enzyme immunohistochemical double-labeling technique could demonstrate only tryptase-positive mast cells; no chymase activity was detectable in any endometrial mast cells. The number of mast cells detected with the metachromatic staining technique was significantly higher than that detected with double labeling. These results support the hypothesis that a sufficient number of mast cells may be necessary for a normal postnatal period and suggest a mast cell subtype in the equine endometrium that is tryptase and chymase negative.

Animals↗
PubMed2002

Dexamethasone inhibits maturation, cytokine production and Fc epsilon RI expression of human cord blood-derived mast cells.

BACKGROUND: Mast cells are responsible for eliciting the early phase and for contributing to the development of the late phase of allergic reactions, through the release of cytokines and other inflammatory mediators. OBJECTIVE: To assess whether the glucocorticoid dexamethasone has a direct effect on mast cell progenitor maturation and on mature cord blood-derived mast cell properties. METHODS: Mast cells were obtained by culturing human umbilical cord blood mononuclear cells with stem cell factor, IL-6 and prostaglandin E2. Mast cell numbers were assessed by Toluidine Blue staining and immunocytochemistry of tryptase positive cells. The expression of Fc epsilon RI, CD49d and c-kit was assessed by flow cytometry. Histamine release was determined by a radioenzymatic assay. Cys-LT, GM-CSF and TNF-alpha production and release were determined by ELISA. RESULTS: Dexamethasone (10(-6) M-10(-9) M) time- and dose-dependently inhibited the maturation of the mast cell progenitors. Dexamethasone did not affect the basal expression of Fc epsilon RI, CD49d and c-kit, but it inhibited the IgE-dependent enhanced expression of Fc epsilon RI. Dexamethasone (10(-6) M-10(-9) M) had no significant effect on Fc epsilon RI-dependent histamine release or the synthesis and release of Cys-LT from the mature mast cells. However, pre-incubation of the mast cell cultures with dexamethasone for 1 h, prior to cross-linking of Fc epsilon RI, dose-dependently inhibited the production and secretion of both GM-CSF and TNF-alpha. CONCLUSIONS: From these in vitro data we propose that glucocorticosteroids are effective drugs in the management of allergic inflammation due to their capacity to inhibit mast cell development, IgE-dependent Fc epsilon RI expression and mast cell production of GM-CSF and TNF-alpha.

Administration, Topical↗
PubMed1985

The effect of 8-methoxypsoralen plus long-wave ultraviolet (PUVA) radiation on mast cells: PUVA suppresses degranulation of mouse skin mast cells induced by compound 48/80 or concanavalin A.

In order to see whether 8-methoxypsoralen (8-MOP) plus long-wave ultraviolet (UVA) radiation (PUVA) has an influence on immediate-type skin reactions, we have undertaken an animal study. Ears of mice were treated with a 0.5% 8-MOP solution topically plus UVA radiation (1.5-2.5 J/cm2). After PUVA radiation, skin responses to intradermal injection with mast cell liberators, including compound 48/80 (2.5 mg/ml, 10 microliter) and concanavalin A (Con-A) (2.0 mg/ml), or with a mixture of 5-hydroxytryptamine (5-HT) and histamine as vasodilator (1.0 mg/ml and 50 mM, respectively) were examined with time (2 h-14 days). At each time point, an ear swelling response (ESR) was measured with a dial thickness gauge. The rate of mast cell degranulation and mast cell numbers were assessed by light microscopy using toluidine blue-stained semithin (1 micron) sections. ESR induced by compound 48/80 or Con-A was significantly suppressed dose-dependently (greater than 42% inhibition) by PUVA between 2 h-3 days postirradiation as compared with that in nonirradiated control mice, and the value returned to normal levels by 7-14 days. Compound 48/80- or Con-A-induced mast cell degranulation (%) was remarkably decreased between 2 h-3 days (greater than 48% inhibition) in accordance with the suppression in ESR and it was restored to the rates in nonirradiated controls by 7-14 days. Neither ESR nor percent degranulation was affected by UVA radiation only (less than 3.5 J/cm2) or application of 8-MOP only. 5-HT plus histamine-mediated ESR was not altered at all by PUVA throughout the experimental period. Since PUVA radiation itself at given doses did not produce measurable ESR, mast cell degranulation, or a reduction in mast cell numbers, and since PUVA did not affect a normal vascular response to vasodilator, it seemed that decreased skin reactivity to mast cell degranulators by PUVA might be due to a PUVA-induced noncytolytic alteration in mast cell release mechanisms.

5-Hydroxytryptophan↗
PubMed1998

Virus-activated CD8 T cells and lymphokine-activated NK cells express the mast cell function-associated antigen, an inhibitory C-type lectin.

The mast cell function-associated Ag (MAFA) is an inhibitory C-type lectin that was originally identified on the cell surface of a rat mucosal mast cell line, RBL-2H3. We have cloned the mouse homologue of the rat MAFA gene, and Northern blot analysis revealed that mouse MAFA (mMAFA) gene expression was strongly induced in effector CD8 T cells and lymphokine-activated NK cells but not in effector CD4 T cells and in mouse mast cells. Moreover, mMAFA gene expression was only found in effector CD8 T cells that had been primed in vivo with live virus because in vitro activated CD8 T cells did not express mMAFA. Primary sequence comparison revealed a high degree of conservation (89% similarity) between rat MAFA and mMAFA. Thus, the MAFA molecule in the mouse is a putative inhibitory receptor on anti-viral CD8 T cells induced in vivo and on NK cells.

Amino Acid Sequence↗
PubMed1988

Cultured human bone marrow-derived mast cells, their similarities to cultured murine E-mast cells.

Homogeneous populations of human mast cells were differentiated and grown by culturing bone marrow cells in the presence of conditioned medium derived from lectin-stimulated human peripheral blood mononuclear cells. The cells obtained were similar in ultrastructure, proteoglycan type and lipid products generated upon calcium ionophore A23187, and immunological activation to the murine E-mast cells (E-MC) differentiated in culture containing IL-3. Fluorescence analysis revealed that the human E-MC expressed IgE-Fc receptors which retained bound IgE through several washes. These cells did not express cell-surface lymphoid determinants (T11, T4, T8 and B4) and myeloid determinants 'My'. However, 40% of these cells expressed monocytic surface determinants, such as M-1. The amount of histamine that was found per 10(6) cells was 525 +/- 106 ng (mean +/- SE, n = 4). These cultured mast cells possessed granular chondroitin sulphate E proteoglycan of about 180,000 MW. Following activation with either calcium ionophore A23187 or anti-hIgE challenge, these mast cells released their preformed mediators and generated mainly leukotriene C4 leukotriene B4, and platelet-activating factor. In conclusion, according to all of these criteria, these human cultured mast cells show many similarities to the murine cultured E-mast cells, and therefore could be considered as the culture analogue of the human intestinal E-mast cells identified recently.

Adult↗
PubMed2006

TGFbeta1 induces mast cell apoptosis.

Mast cells are potent effectors of the inflammatory response, playing an important role in atopy, bacterial immunity, and animal models of arthritis, multiple sclerosis, and heart disease. Hence controlling mast cell numbers and responsiveness is essential for preventing inflammatory disease. We demonstrate that the cytokine transforming growth factor (TGF) beta1 is a potent inducer of mast cell apoptosis, a finding that was consistent in cultured mouse bone marrow-derived mast cells, peritoneal mast cells, and human mast cells. Cell death appeared to be caused by TGF-mediated repression of interleukin-3 (IL-3) receptor expression and function, leading to mitochondrial damage and activation of an apoptotic cascade acting via p53 and caspases. Although IL-3 receptor expression was reduced within 1 day of TGFbeta1 stimulation, apoptosis required at least 3 days to occur. This delay in onset is postulated to allow protective mast cell effector functions, protecting the host from infection while preventing the establishment of chronic inflammation. Our data support the theory that TGFbeta1 is an inhibitor of mast cell survival. The widespread expression of TGFbeta1 offers this cytokine as an ideal candidate for control of mast cell homeostasis.

Animals↗