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PubMed1991

Ultrastructural and immunohistochemical characterization of normal mast cells at multiple body sites.

This article reviews the ultrastructural and immunohistochemical features of normal human mast cells (MC) at multiple tissue sites. Current literature indicates that granules containing discrete scrolls (scroll-rich morphology) are frequent in MC from bowel mucosa and lung, locations where the majority of MC show only tryptase immunoreactivity (MCT). In contrast, most MC from skin, breast parenchyma, axillary lymph nodes, and bowel submucosa are characterized by scroll-poor morphology (that is, granules are rimmed by incomplete scrolls forming parallel lamellae and containing central, amorphous granular material or grating/lattice-like structures) and show both tryptase and chymase immunoreactivity (MCTC). MC having granules with both scroll-rich and scroll-poor features can occur in all tissue sites, and an occasional MC, especially in lung and bowel, may show only chymase immunoreactivity (MCC). Chymase immunoreactivity in MC also is closely associated with avidin binding and carboxypeptidase reactivity. We conclude that there is ultrastructural and immunophenotypic diversity among normal human MC, although certain forms predominate in specific tissue environments. In skin, breast tissue, axillary lymph nodes, and bowel submucosa MC tend to have scroll-poor granules and stain for avidin, chymase, tryptase, and carboxypeptidase, whereas, in lung and bowel mucosa MC granules tend to be scroll-rich and stain only for tryptase with currently available reagents.

Breast↗
PubMed1989

Mast cell chymase. A potent secretagogue for airway gland serous cells.

Submucosal glands are the major sources of airway secretions in most mammals. Mast cells are abundant in the environment of airway submucosal glands and are rich sources of secreted proteases. To investigate the hypothesis that mast cell proteases stimulate airway gland secretion, we studied the ability of the two major mast cell granule proteases, chymase and tryptase, to cause secretion of 35S-labeled macromolecules from a line of cultured bovine airway gland serous cells. Mast cell chymase and tryptase were purified from dog mastocytoma cells. Chymase markedly stimulated serous cell secretion in a concentration-dependent fashion with a threshold of 10(-10) M, whereas tryptase had no effect. The response to 10(-8) M chymase (1530 +/- 80% over base line) was approximately 10-fold higher than that evoked by other agonists such as histamine and isoproterenol. The predominant 35S-labeled macromolecule released by chymase was chondroitin sulfate proteoglycan, the glycoconjugate present in serous cell secretory granules. The response to chymase was non-cytotoxic and was blocked by active site inhibitors of chymase (soybean trypsin inhibitor and chymostatin) and by inhibitors of cellular energy metabolism (azide,2,4-dinitrophenol, dicumarol). Supernatant obtained by degranulation of mastocytoma cells caused a secretory response of comparable magnitude to that caused by chymase. These findings demonstrate that chymase, but not tryptase, is a potent secretagogue for airway gland serous cells, and they suggest a possible role for chymase-containing mast cells in the pathogenesis of airway hypersecretion.

Animals↗
PubMed1989

Ultrastructural analysis of maturing human T and TC mast cells in situ.

Mast cells at immature stages of development were identified in human tissues by electron microscopic techniques. General morphologic criteria of immaturity (such as a high apparent nuclear:cytoplasmic ratio and small cell size), the presence of few granules (those present being smaller than those in mature mast cells) and a lack of features of mast cell activation were used together to determine the level of maturity. Mast cells were identified as being of the T or TC type by immunogold staining with polyclonal rabbit IgG anti-chymase and murine monoclonal anti-tryptase primary antibodies and the appropriate gold-labeled secondary antibodies. Only those cells with tryptase-positive granules were recognized as mast cells. Immature T mast cell granules contained the same characteristic discrete scrolls found in their mature counterparts and all stained positive for tryptase. The presence of trace amounts of chymase in a minority of these granules, as in mature T mast cells, could not be ruled out. The majority of granules in immature TC mast cells had one or more amorphous electron-dense cores rather than the grating and lattice substructures characteristic of granules in mature TC mast cells. Secretory granules in immature TC mast cells stained positively for tryptase and chymase. Occasional immature TC mast cells contained a complete granule or a portion of a granule with the substructure characteristic of mature TC mast cells, favoring the concept that these TC mast cell forms are developmentally related. Essentially all mast cells in foreskin of newborns appeared immature, whereas 10, 5, 10, and 15% of the mast cells in adult lung, foreskin, bowel mucosa and bowel submucosa, respectively, appeared immature. The distribution of T and TC types of immature mast cells seemed to parallel that of the mature mast cell types. These compositional and ultrastructural differences between immature T and TC types of mast cells suggest that from the time granule formation begins, and possibly before this time, each type of human mast cell follows a distinct developmental pathway.

Adult↗
PubMed1999

Hyperfibrinolysis in a case of myelodysplastic syndrome with leukemic spread of mast cells.

Mast cells (MC) are multipotent hemopoietic effector cells producing diverse mediators like histamine, heparin, or tissue type plasminogen activator. We report a 75-year-old male patient with myelodysplastic syndrome (MDS) of recent onset (3 months' history) associated with a massive leukemic spread of immature tryptase+ MC (tentative term: myelomastocytic leukemia). The patient presented with pancytopenia, bleeding, hypofibrinogenemia, and an increased cellular tryptase level. Moreover, an excessive elevation of plasmin-antiplasmin complexes (9,200 ng/ml; normal range: 10-150), an elevated D-dimer, and an increase in thrombin-antithrombin III complexes were found. The identity of the circulating MC was confirmed by immunophenotyping (CD117/c-kit+, CD123/IL-3R alpha-, CD11b/C3biR-), biochemical analysis (cellular ratio [ng:ng] of tryptase to histamine >1), and electron microscopy. Bone marrow (bm) examination showed trilineage dysplasia (17% blasts), 30% diffusely scattered MC, and a complex karyotype. No dense, compact MC infiltrates (mastocytosis) were detectable in bm sections. Despite hyperfibrinolysis and mediator syndrome (flushing, headache), the patient received remission induction polychemotherapy (DAV) followed by two cycles of consolidation with intermediate dose ARA-C (2 x 1 g/m2/day on days 1, 3, and 5). He entered complete remission after the first chemotherapy cycle without evidence of recurring MDS. Moreover, in response to chemotherapy, the hyperfibrinolysis and mediator syndrome resolved, and the circulating c-kit+ MC disappeared. We suggest consideration of polychemotherapy as a therapeutic option in patients with high-risk MDS of recent onset, even in the case of MC lineage involvement.

Aged↗
PubMed2006

Number of pericryptal fibroblasts correlates with density of distinct mast cell phenotypes in the crypt lamina propria of human duodenum: implications for the homeostasis of villous architecture.

Pericryptal fibroblasts (PFs), a class of myofibroblasts, have strongly been implicated in the regulation of villous structure because of their location close to crypts and their ability to secrete cytokines affecting intestinal epithelial cell proliferation and differentiation. Recently, mast cells (MCs) have also been involved in the homeostasis of villous architecture. As myofibroblasts arise in a wide variety of settings concurrently with a local increase in the number of tissue MCs, we calculated in this study the density of both PF and distinct pericryptal MC phenotypes in the mucosa of human duodenum showing normal, defective, or atrophic villous profiles. In addition, we evaluated the statistical association between PF-MC densities and each pattern of villous architecture. Finally, we correlated the density of PF with the density of pericryptal MC phenotypes. For this purpose, samples taken by endoscopy from 30 patients complaining of inflammatory bowel disorders were studied by immunohistochemistry. The densities of alpha-smooth muscle actin-positive PFs as well as tryptase-, chymase-, and c-kit-positive MCs were determined in the crypt lamina propria. Villous architecture was found to be significantly associated with the number of PFs and tryptase-, chymase-, c-kit-positive MCs in the lamina propria (ANOVA group effect P < 0.001). High density of both PFs and MCs was found in intestinal samples with normal villous morphology while lower densities were associated with defective or atrophic villous profiles (Tukey's test for multiple comparison P < 0.001). In addition, a significant correlation was found between PF density and the density of each pericryptal MC phenotype (vs. tryptase-positive MCs, r = 0.913; vs. chymase-positive MC, r = 0.905; vs. c-kit-positive MC, r = 0.927; P < 0.001 in all cases). This study provides morphological support for an important cooperation between PFs and MCs in maintaining normal villous architecture.

Actins↗
PubMed1996

Human synovial mast cells. I. Ultrastructural in situ and in vitro immunologic characterization.

OBJECTIVE: To examine the ultrastructure of human synovial mast cells in situ, to identify immunologic and nonimmunologic stimuli that activate these cells in vitro, and to quantify a number of preformed and de novo-synthesized mediators. METHODS: We conducted an ultrastructural study of synovial mast cells in situ and performed immunoelectron microscopy localization of tryptase and chymase. Isolated synovial mast cells were analyzed biochemically, immunologically, and functionally in vitro and compared with cells from human lung, heart, and skin. RESULTS: Ultrastructural study of synovial tissue revealed mast cells with homogeneously dense, scrolled, crystal, and mixed granules, and lipid bodies in the cytoplasm. A small percentage of mast cells showed evidence of degranulation. Immunoelectron microscopy demonstrated the subcellular localization of tryptase and chymase over granules of > 90% of the mast cells, which were of the MCTC subtype. Isolated synovial mast cells released histamine in response to immunologic (anti-IgE and anti-Fc epsilon receptor I [anti-Fc epsilon RI]) and nonimmunologic (substance P, recombinant human stem cell factor, and 48/80) stimuli, but did not respond to recombinant human C5a in vitro. Synovial mast cells differed from those isolated from other human tissues, in a variety of immunologic and biochemical features. There was a linear correlation between the percentage of histamine secretion and tryptase release (r = 0.79, P < 0.001) induced by cross-linking of Fc epsilon RI. Cross-linking of IgE with anti-IgE on synovial mast cells induced de novo synthesis of prostaglandin D2 (mean +/- SEM 87.5 +/- 4.9 ng/10(6) cells) and of leukotriene C4 (57.6 +/- 17.8 ng/10(6) cells). CONCLUSION: Mast cells ultrastructurally characterized in situ in synovial tissue were seen to differ from mast cells previously isolated from other human tissues. This raises the possibility that the local microenviroment influences their phenotype. Isolation of mast cells from human synovia can be useful for studying their role and their mediators in patients with arthritis.

Adult↗
PubMed2003

Mast cell inhibitor cromolyn increases blood clotting and hypoxia in murine breast cancer.

Human breast cancer is extensively infiltrated by mast cells that contain powerful anticoagulants such as heparin, tryptase and chymase. To determine if human breast cancer is associated with mast cell activation, we measured the levels of mast cell tryptase (an indicator of mast cell activation) in the blood of 20 women with varying stages of breast cancer. The mean level of tryptase in women with breast cancer (10.3 +/- 4.2 microg/L) was significantly higher than in 50 normal healthy women without breast cancer (3.0 +/- 2.5 microg/L, p < 0.05 by two-tailed t-test). To explore the role of mast cells in breast cancer in more detail, we then carried out experiments that were aimed at determining if an inhibitor of mast cell function, sodium cromolyn, could increase blood clotting and hypoxia within subcutaneous implants of the 4T1 mammary adenocarcinoma cell line in mice. We treated tumor-bearing mice with 5 consecutive daily doses of sodium cromolyn (10 mg/kg, i.p.). An average of 30% of the periphery of the tumors from the 5 drug-treated mice contained large lakes of clotted blood that were not evident in any of the tumors from the control (untreated) mice. By computerized image analysis of tumors immunostained for a hypoxia marker (pimonidazole), the tumors from the treated mice had significantly more hypoxia (35 +/-12 % hypoxic regions, n = 5) than the tumors from untreated (control) mice (16 +/- 7%, n = 5). We conclude that sodium cromolyn enhanced peri-tumoral blood clotting and intratumoral hypoxia. These results suggest that mast cells may play an important role in regulating blood clotting and hypoxia within breast cancer.

Adenocarcinoma↗
PubMed1997

Soybean Bowman-Birk protease inhibitor is a highly effective inhibitor of human mast cell chymase.

Soybean Bowman-Birk protease inhibitor (BBI) is an inhibitor of serine proteases with two functional inhibitory domains of different specificities: one is specific for chymotrypsin-like proteases, the other for trypsin-like proteases. Chymase and tryptase are serine proteases which are stored in mast cell granules and released upon degranulation. This work investigated the inhibition of human chymase and tryptase by BBI. Active-site titration of human skin chymase by BBI demonstrated that BBI was a highly effective inhibitor of human chymase. Virtually stoichiometric inhibition of chymase by BBI was observed at 10 nM chymase. Kinetic studies of the inhibition reaction yielded an association rate constant of 4.0 x 10(5) M(-1) s(-1) and a dissociation rate constant of 1.7 x 10(-5) s(-1). From these two constants we estimate a K(i) of 50 pM. Chymase/BBI complexes did not dissociate in SDS-PAGE analyses under nonreducing conditions, consistent with the formation of a very tight complex with little tendency to dissociate. In contrast to chymase, human tryptase was not inhibited by BBI. These studies demonstrate that BBI is a good inhibitor of human chymase, exhibiting reaction properties better than physiological inhibitors described to date.

Binding Sites↗
PubMed1997

Markers of mast cell degranulation.

Mast cells are the primary effector cells of immediate hypersensitivity reactions in humans. Upon mast cell activation both preformed and newly synthesized mediators are secreted. Histamine can be measured by fluorometric assays, radioenzymatic assays, and immunoassays. These methods have been applied to plasma and urine to detect histamine that had been released in vivo and to release histamine in vitro from basophils and mast cells. Another mast cell constituent is tryptase, which is a more selective marker of mast cells, because negligible amounts are found in basophils. beta-Tryptase is stored in secretory granules and is actively released when mast cells degranulate. alpha-Protryptase remains in the proenzyme form and is constitutively released from mast cells, and consequently its level in serum reflects total numbers of mast cells. alpha-Protryptase levels are elevated in serum at baseline in subjects with systemic mastocytosis, whereas beta-tryptase is elevated in serum from subjects with systemic anaphylaxis. These markers serve as precise clinical indicators of the involvement of mast cells in human disease.

Anaphylaxis↗
PubMed1994

Phenotypic evaluation of cultured human mast and basophilic cells and of normal human skin mast cells.

In order to evaluate various markers for human mast cells, two human mast/basophilic cell lines (HMC-1/KU812), cultured mast cells from the peripheral blood monocytic fraction and peripheral blood monocytes were compared with mast cells in tissue sections from normal skin, using histochemistry, enzyme histochemistry and immunohistochemistry. All reagents stained normal skin mast cells, with toluidine blue, tryptase reactivity and antibodies against the Fc epsilon RI and the stem cell factor receptor (c-kit) being most active. The cell lines and mast cells cultured from peripheral blood were negative for avidin, safranin and chymase, strongly positive for c-kit and variably reactive with all other reagents. All antibodies except AA1 against tryptase also stained one or several epidermal and dermal cell types or blood monocytes. Histochemical stains (toluidine blue, avidin) and reagents for the enzymes tryptase and chymase are thus specific markers for mast cells. The frequent reactivity of antibodies against mast cells with other cell types indicates interesting functional and ontogenetic relationships between these cells.

Antibodies, Monoclonal↗
PubMed2000

The effects of S1319, a novel marine sponge-derived beta2-adrenoceptor agonist, on IgE-mediated activation of human cultured mast cells.

OBJECTIVE: This study aimed to evaluate the ability of S1319 (4-hydroxy-7-[1-(1-hydroxy-2-methylamino) ethyl]-1,3-benzothiazol-2(3H)-one acetate), a novel beta2-adrenoceptor selective agonist derived from marine sponge, to inhibit IgE-mediated activation of human cultured mast cells (HCMC) in vitro. MATERIALS AND METHODS: We examined the effect of S1319 (racemate) on tryptase release and tumor necrosis factor-alpha (TNF-alpha) production in HCMC generated from human cord blood cells, after cross-linking of high affinity immunoglobulin E receptors (FcepsilonRI), compared with those of the nonselective beta-adrenoceptor agonist, isoproterenol (R-isomer), the selective beta2-adrenoceptor agonist, salbutamol (racemate), and the selective and long-acting beta2-adrenoceptor agonist, formoterol (racemate). We also evaluated the effect of S1319 on the intracellular cAMP level, inositol phosphate production and protein tyrosine phosphorylation in HCMC. RESULTS: S1319 and beta-adrenoceptor agonists inhibited the IgE-mediated release of tryptase. Approximate IC50 values of S1319, formoterol, isoproterenol and albuterol for the inhibition of tryptase release were 0.51+/-0.12, 0.15+/-0.1, 0.80+/-0.09, and 28+/-32.4 nM, respectively. S1319 and beta-adrenoceptor agonists also inhibited TNF-alpha production by HCMC in a concentration-dependent manner. Approximate IC50 values of S1319, formoterol and isoproterenol for the inhibition of TNF-alpha production were 0.19+/-0.03, 0.28+/-0.02 and 0.32+/-0.03 nM, respectively. S1319 caused a concentration-dependent increase in total cell cyclic AMP levels in HCMC. On the other hand, S1319 inhibited the accumulation of inositol 1,4,5-triphosphate and IgE-mediated protein tyrosine phosphorylation of 42-kDa protein, p42 mitogen activated protein (MAP) kinase (ERK-2). CONCLUSION: These results indicate that S 1319 and beta-adrenoceptor agonists are potent inhibitors of the IgE-mediated release of mediators from HCMC.

Adrenergic beta-Agonists↗
PubMed2000

Mast cell derangement in salivary glands in patients with Sjögren's syndrome.

Mast cells (MCs) have been implicated in many immune-inflammatory disorders. Deranged mast cell distribution and function may contribute to the local pathomechanisms in the labial salivary glands (LSG) in Sjogren's syndrome (SS). Evidence for MC presence, localization, frequency, subtype, and degree of activation was sought by using reverse transcriptase-polymerase chain reaction (RT-PCR), immunohistochemistry (IHC)/image analysis, transmission electron microscopy, Western blotting, spectrophotometric activity assay, and radioimmunoassay. The overall expression (densitometric units) of MC tryptase mRNA (1483 +/- 228 vs 1044 +/- 308) did not differ between SS and control LSGs. However, IHC disclosed an uneven distribution of MCs in SS with an absence in lymphocyte foci and increased numbers (cells/mm2 77 +/- 7 vs 38 +/- 4, P < 0.01) elsewhere. Absence of MCs in the lymphocyte foci was not a fixation artefact and was not explained by the presence of "phantom" MCs in these areas. In both SS and controls, 80% of all MCs were chymase containing, but the typical lattices/gratings characteristic for connective tissue MCs (CTMCs) were not found. Instead, MC granules had mostly a homogeneous, finely granular substructure characteristic of "new" granules subjected to a continuous, low-grade release. 32 kDa MC tryptase was found in saliva and its activity/concentration was comparable to that found in controls. However, tryptase output was low in SS (1.30 +/- 0.30 microg/min vs 3.49 +/- 0.66 microg/min, P < 0.001). Normal LSGs contain mostly CTMCs, in close contact with various resident and immigrant cells, characterized by a low-grade release of MC mediators. In SS this normal pattern is disturbed so that MCs are absent in lymphocyte foci (but increased elsewhere in the glands). The net salivary output of MC mediators is low in SS. This derangement of MCs may contribute to the pathogenesis of SS via multiple mechanisms.

Adult↗
PubMed2002

Quantitative analysis of bikunin-laden mast cells in follicular eruptions and chronic skin lesions of atopic dermatitis.

Bikunin, an inhibitor of serine proteases, is widely distributed in human tissues, including the skin, and may inhibit tryptase and modulate allergic inflammation. The purpose of the present study was to compare follicular eruptions (FE), so-called atopic skin or perifollicular accentuation, with atopic dermatitis (AD) lesions (ADL) by immunohistochemical analysis using antibodies to bikunin and tryptase. Immunohistochemically, bikunin was colocalized with tryptase in dermal mast cells, and a small quantity of bikunin was also deposited in the intercellular spaces in FE and ADL. The number of bikunin-laden mast cells per 0.78 mm(2) of skin was 78.1+/-7.1 (mean+/-SEM, n=14) in FE, 25.4+/-2.3 (n=10) in normal skin from children and infants, 91.3+/-11.8 (n=10) in ADL, 25.6+/-4.8 (n=5) in nonlesional skin of AD, and 27.8+/-2.0 (n=13) in normal adult skin. The difference between FE and normal control skin from children and infants, between FE and nonlesional skin of AD, and between lesional and nonlesional skin of AD were significant. Based on the above findings and the occasional presence of spongiosis and lymphocyte infiltration, in FE moderate inflammation is apparent histopathologically even though little inflammation is apparent clinically.

Adolescent↗
PubMed2000

Nasal and bronchial responses to flour-inhalation in subjects with occupationally induced allergy affecting the airway.

OBJECTIVES: The aim of the study was to follow the similarities and differences, of cellular and mediator changes and mucosal/vascular permeability in the upper and lower airway after specific and nonspecific bronchial provocation, in bakers with diagnosed occupationally induced allergy affecting the airway. In addition, the authors try to find whether there is a relationship between cellular changes in nasal and bronchoalveolar lavage, and bronchial hyperreactivity. METHODS: The study participants were 10 bakers with occupational bronchial asthma and allergic rhinitis. All patients were sensitized to investigated allergen-flour. Nasal- and bronchoalveolar lavage techniques were used to evaluate the changes of the cellular and mediator response (tryptase, eosinophil cationic protein, ECP) and albumin level after specific (flour) and placebo provocation. In addition. bronchial hyperreactivity for histamine, and forced expiratory volume in 1 s (FEV1) were measured after the challenge. RESULTS: There was a significant increase in the percentage of eosinophils, basophils and albumin in nasal and bronchoalveolar lavage of occupationally sensitized bakers. A statistically significant increase in the percentage of neutrophils in bronchoalveolar lavage was observed only 24 h after the allergen challenge. The level of tryptase in nasal lavage was significantly higher during the early allergic response. The levels of ECP in both nasal and bronchoalveolar lavage were significantly increased during the late allergic response. There were also severe bronchial reactions and increase of bronchial hyperreactivity for histamine in occupationally sensitized bakers in the late phase of allergic reaction. CONCLUSION: Eosinophils and basophils proved to be the predominant cells in nasal and bronchoalveolar lavage of patients with occupationally induced bronchial asthma and rhinitis. The prolonged increase of albumin level seems also to be a good predictor of protracted nasal and bronchial inflammation. The results obtained confirmed that tryptase and ECP are good markers for monitoring mast cell and eosinophil degranulation during the allergic reaction. Increase of airway responsiveness reflects an eosinophil and basophil contribution to airway allergic response.

Adult↗
PubMed2003

Chymase-positive mast cells in small sized adenocarcinoma of the lung.

Mast cells accumulate in angiogenesis-dependent situations of lung adenocarcinoma. Human mast cells are divided into two major subsets: MCT (mast cells with immunoreactivity for tryptase but not chymase) and MCTC (reactive for tryptase and chymase). Chymase is an important mediator of tissue remodeling, but research into chymase-containing mast cell subpopulations has been hampered by the lack of reagents suitable for use with formalin-fixed tissue. We stained chymase using CC1 antibody in 66 cases of small sized lung adenocarcinoma as well as CD34 and tryptase. There were significant positive correlations of microvessel counts with MCT-type and MCTC-type mast cell counts in lung adenocarcinomas. When analyzed according to Noguchi's classification, MCT-type and MCTC-type mast cells were significantly increased in Noguchi type-C tumors [localized bronchioloalveolar carcinoma (LBAC) with active fibroblastic proliferation] compared with in Noguchi type-A (LBAC) plus type-B tumors (LBAC with alveolar collapse). Members in the high-count group of MCTC-type but not MCT-type mast cells showed a significantly worse outcome than those in the low-count group in LBACs. Counting chymase-positive (MCTC-type) mast cells in tumor stroma may be a good prognosis predictor for LBACs, especially Noguchi type-C tumors.

Adenocarcinoma↗
PubMed1998

Distribution of intrahepatic mast cells in various hepatobiliary disorders. An immunohistochemical study.

There is evidence that mast cells are involved in a number of pathophysiological processes. The significance of mast cells in hepatic fibrosis was examined in 28 patients with histologically normal livers, 34 with acute liver diseases, 51 with chronic liver diseases, and 59 with cholestatic biliary diseases, using immunostaining of the mast cell-specific proteinase, tryptase. Mast cells that were positive for tryptase and for chymase were significantly increased in frequency in fibrotic portal tracts and fibrous septa, particularly in cholestatic/biliary diseases. Mast cells were also increased in frequency around the fibrotic septal and intrahepatic large bile ducts and peribiliary glands of biliary diseases. However, they were less common or even rare in the sclerotic bile ducts and in scarred portal or septal fibrosis. More than half of these more numerous mast cells were positive for histamine, and some were also positive for basic fibroblast growth factor. These two substances were detectable by immunoelectron microscopic in the cytoplasmic granules of mast cells. In contrast, mast cell numbers were not significantly increased in acute viral or drug-induced hepatitis, or in zones 2 and 3 of the hepatic acinus with respect to pericellular and perivenular fibrosis in chronic liver diseases. These findings suggest that mast cells increase in number in cholestatic/biliary diseases, and to a lesser degree in chronic liver diseases, and are involved in the active fibrous enlargement of portal tract and fibrous septa formation and also in the fibrosis of the intrahepatic bile ducts as they display fibrosis-promoting factors such as tryptase, fibroblast growth factor and histamine.

Acute Disease↗
PubMed1996

A comparison of cysteine and serine proteinases in human gingival crevicular fluid with tissue, saliva and bacterial enzymes by analytical isoelectric focusing.

Gingival crevicular fluid (GCF) contains several different proteinase activities and the study sought to clarify their sources. Gingival tissue and GCF were collected from chronic periodontitis patients. Gel-filtration chromatography of crude tissue extracts yielded cathepsin B and tryptase fractions sensitive to cysteine and serine proteinase inhibitors, respectively. Cell sonicates of suspected periodontal pathogens were prepared from broth cultures of reference strains. Of these, Porphyromonas gingivalis showed much the strongest activity and this had an effector response consistent with the metal-dependent cysteine proteinase described by others. Banding patterns in GCF, tissue and bacterial samples were compared on substrate-impregnated overlay membranes applied to isoelectric focusing gels. On Z-Val-Lys-Lys-Arg-AFC overlays, GCF had bands corresponding to tissue cathepsin B and the enzyme from P. gingivalis, though a contribution from Treponema denticola could not be ruled out. Use of D-Val-Leu-Arg-AFC overlays showed GCF activity similar to tissue tryptase. In GCF there were additional bands that did not correspond to any tissue or bacterial samples and on Z-Ala-Ala-Lys-AFC overlays these closely resembled activity in parotid saliva. The results confirmed that GCF contains tissue cathepsin B and tryptase, while the apparent presence of enzymes from P. gingivalis and possibly T. denticola is consistent with previous reports linking activity to these organisms. The saliva bands demonstrated that contamination of GCF may occur despite rigorous collection procedures.

Bacteria↗
PubMed1996

Mast cells accompany microvessels in human coronary atheromas: implications for intimal neovascularization and hemorrhage.

Mast cells have been assigned a role in neovascularization. Therefore, we examined the deep regions of human coronary atheromas, the areas known to be prone to neovascularization, for the presence of mast cells. Specimens of atherosclerotic human coronary intima from 37 autopsy cases with ages of 24-84 years were stained with elastica-van Gieson to detect atheroma formation and with monoclonal antibody against von Willebrand factor to detect neovascularization. Mast cells were detected by staining the atheromas with monoclonal antibodies against the two major proteases of mast cells, tryptase and chymase. Of the 24 coronary atheromas found, 13 contained mast cells in the deep regions. All these 13 deep regions also displayed neovascularization, and the number of microvessels and the number of mast cells around the microvessels correlated strongly with the size of the atheroma. On the other hand, of the 11 deep regions lacking mast cells, only one displayed neovascularization. In the neovascularized areas of the coronary atheromas, the mast cells were in close proximity to the microvessels. All the mast cells contained tryptase, and some of them chymase, both known for their angiogenic and matrix-degrading potential. In light microscopic studies, degranulated mast cells were observed indicating activation of these cells, with release of tryptase and chymase. The selective localization of activated mast cells containing angiogenic factors around newly formed microvessels in human coronary atheromas suggests that mast cells play a role in the neovascularization of these lesions. Moreover, mast cells may also, by virtue of their neutral proteases, injure the microvessels, and thereby produce intraplaque hemorrhages and, ultimately, unstable lesions.

Adult↗