Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human fetal liver cells cultured in the presence of recombinant human stem cell factor (rhuSCF) give rise to highly purified mast cell populations. This study examined the effect of steroid hormones on mast cell differentiation. Dispersed fetal liver cells cultured in the presence of rhuSCF at 50 ng/ml and in the presence or absence of various steroid hormones for 4 weeks, were analysed for the presence of mast cells by metachromatic staining with toluidine blue, by immunohistochemistry with a monoclonal antibody against tryptase, and by immunofluorescent flow cytometry with a monoclonal antibody against Kit. Dexamethasone added to the cultures at day 0 resulted in a dose-dependent inhibition of rhuSCF-induced mast cell differentiation with > 85% inhibition seen at a dose of 10(-6) M. A similar effect was seen with hydrocortisone, but not with oestradiol or progesterone. The addition of dexamethasone resulted in decreased DNA synthesis in 14-day-old cultured cells, as assessed by incorporation of bromodeoxyuridine. Addition of dexamethasone to 3-week-old SCF-dependent fetal liver mast cells had no significant effect on mast cell survival. Removal of dexamethasone after 3 weeks of culture with SCF did not result in mast cell development. Thus, dexamethasone inhibits SCF-induced development of mast cells from fetal liver cells, but shows no appreciable effect on developed mast cells.
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PMID:Dexamethasone inhibits the development of mast cells from dispersed human fetal liver cells cultured in the presence of recombinant human stem cell factor. 753 66

Besides stem cell factor (SCF), additional fibroblast-derived mast cell growth factors have previously been described. Since keratinocytes have also been shown to produce SCF, we have studied the ability of culture supernatants from the human HaCaT keratinocyte cell line to induce SCF-independent mast cell differentiation. The immature human mast cells of the HMC-1 line which express a mutant continuously activated SCF receptor were used as model target cells. Culture supernatants from differentiating keratinocytes (at day 11 of culture), and far less so those from proliferating keratinocytes (day 4 of culture), caused a marked, dose-dependent increase of histamine and tryptase in HMC-1 cells. This suggests that human HaCaT keratinocytes release mast cell differentiation factors other than SCF, to a degree related to their state of differentiation.
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PMID:Human keratinocytes release mast cell differentiation factors other than stem cell factor. 754 60

Human fetal livers contain progenitor cells that become mast cells after 4 weeks of culture with recombinant human stem cell factor. Expression of cell surface CD29 (beta 1), CD18 (beta 2), CD61 (beta 3), and beta 5 integrins was investigated on such cells by flow cytometry and adhesion measurements. High surface expression of CD49e, CD51, and CD61 along with kit was apparent by 4 weeks of culture, whereas expression of each at day 0 was low to undetectable. CD29 and CD49d were detected on cells from day 0 to 4 weeks of culture; CD49b, CD49c, CD49f, CD18, and CD54 expression was negligible. The fetal liver-derived mast cells spontaneously adhered to vitronectin. No evidence for degranulation was found during vitronectin-dependent adhesion. Adhesion occurred in part through the CD61/CD51 receptor. No evidence for adhesion to vitronectin through CD29 and beta 5 integrins was obtained. Almost all of the vitronectin-adherent cells expressed CD51, CD61, kit, and tryptase, and exhibited metachromasia with toluidine blue. Thus, among the fetal liver-derived cells, developing mast cells were selectively adherent to vitronectin. These mast cells and the other cell types present also adhere spontaneously to fibronectin and to laminin, this adhesion being partially inhibited by antibodies against CD61 and CD29 integrins. In conclusion, human mast cells acquire functional vitronectin receptors as they develop from fetal liver progenitors under the influence of rhSCF. This may be important for the recruitment, localization, and retention of developing mast cells.
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PMID:Human mast cells derived from fetal liver cells cultured with stem cell factor express a functional CD51/CD61 (alpha v beta 3) integrin. 754 4

The extracts from rat submandibular glands (SMGs) induced erythroid differentiation of K-562. The activity was non-dialysable and abolished by heat, trypsin or 2-mercaptoethanol. Follistatin, which neutralizes the erythroid differentiation factor (EDF), had no effects on this activity. Analysis by gel chromatography and polyacrylamide gel electrophoresis-isoelectric focussing showed that the characteristics of this substance were different from those of erythropoietin, TGF-beta 1, EDF, stem cell factor and insulin-like growth factor-1. These results suggest the presence of a novel substance in rat SMGs which induces erythroid differentiation of K-562.
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PMID:The extracts from rat submandibular glands induce the erythroid differentiation of K-562 cells. 759 52

The recently cloned interleukin 13 (IL-13) shares most investigated biological activities on B lymphocytes and monocytes with IL-4. In this study we investigated the potential role of IL-13 in regulating human mast cell activities. The effects of IL-13 on the expression of an immediate-early response gene (c-fos), proliferation, expression of mast cell-associated cell surface antigen (CD54 and Kit), and in vitro differentiation of human mast cells, were investigated. We compared the effect of IL-13 with that of IL-4. Both IL-13 and IL-4 induced expression of c-fos in cells from the human mast cell line HMC-1. This indicates that mast cells express functional receptors for IL-13. IL-13 and IL-4 decreased the proliferation rate of HMC-1 cells. However, IL-13 was less potent than IL-4. Human mast cells constitutively express the adhesion molecule ICAM-1 (CD54) and the receptor for stem cell factor (Kit) (CD117). The expression of CD54 was increased after treatment with IL-13 or IL-4, whereas the expression of Kit was decreased. Also in this action IL-4 was more potent than IL-13. By culturing mononuclear cells from cord blood in the presence of stem cell factor there is a differentiation of tryptase-positive mast cells in the cultures. This process was inhibited when IL-4 was present. In contrast, IL-13 did not affect the expression of tryptase during differentiation of stem cell factor dependent cord blood-derived mast cells. Taken together, these findings indicate that IL-13 has regulatory effects on human mast cells. The effect overlaps with but is also different from that of IL-4.
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PMID:Effects of interleukin (IL)-13 on immediate-early response gene expression, phenotype and differentiation of human mast cells. Comparison with IL-4. 770 21

Mast cell neutral proteases are the most precise markers of heterogeneity among human mast cells. Two types of human mast cells have been recognized. MCTC cells contain tryptase together with chymase, cathepsin-G like protease, and mast cell carboxypeptidase; MCT cells contain tryptase, but lack the other neutral proteases present in MCTC cells. All mast cells develop from hemopoietic stem cells. In vitro procedures for studying mast cell growth have been developed, using the major human mast cell growth factor, stem cell factor (SCF, also called Kit-ligand). Cultures of hemopoietic progenitor cells in the presence of SCF alone result in selective differentiation to mast cells. The same progenitor cells can be induced to differentiate into other lineages when SCF is used with various lineage-specific colony-stimulating factors such as erythropoietin for erythrocytes. Mast cell development from hematopoietic progenitors may represent a "default pathway," occurring optimally in a permissive microenvironment such as skin, bowel, and lung. The presence or absence of certain cytokines in blood and bone marrow may create a non-permissive environment, thus the absence of granulated mast cells in such locations.
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PMID:Human mast cell heterogeneity. 772 Oct 78

To determine the fate of Fc epsilon RI+ cells on fibroblasts in vitro, human bone marrow derived CD34+ cells were cultured in the presence of recombinant human interleukin 3 and recombinant human hematopoietic stem cell factor for 3 weeks, and Fc epsilon RI+ cells were purified by immunomagnetic selection. This enriched Fc epsilon RI+ cell population consisted of 92-94% basophils and 3-5% mast cells as determined by morphologic, immunohistochemical, and ultrastructural criteria. The Fc epsilon RI+ cells were then cocultured with 3T3 fibroblasts. Basophils decreased markedly by 1 week and were absent from cocultures by 2-3 weeks, while the mast cell numbers on the fibroblast monolayers remained constant. Ultrastructural examination of cocultures at 2 days demonstrated phagocytosis of basophils by fibroblasts. By 1 week, phagocytosed basophil membranes and granules gave fibroblasts the superficial appearance of mast cells by toluidine blue staining. Mast cells surviving in cocultures could be distinguished from granule-containing fibroblasts by IgE surface labeling and by ultrastructural demonstration of tryptase-positive granules. Thus, while mast cells remain viable in coculture with 3T3 fibroblasts, basophils do not survive and are internalized and degraded by the fibroblast monolayer.
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PMID:Fibroblasts determine the fate of Fc epsilon RI+ cell populations in vitro by selectively supporting the viability of mast cells while internalizing and degrading basophils. 798 8

A murine colony-promoting activity (CPA) was found in the supernatants of Dexter long-term bone marrow cultures (LTBMC). This activity itself failed to stimulate in vitro granulocyte-macrophage colony (CFU-GM) formation but could increase the number of colonies induced by colony-stimulating factors (CSFs). CPA was produced by the adherent stromal cells but not by the nonadherent cells. No CPA could be detected in cultures of pure marrow fibroblasts, nor was it secreted by the stromal cells following macrophage depletion. In contrast, a large amount of CPA was found in cultures of isolated macrophages, suggesting that marrow macrophages may be the main cell source of CPA. Although colony formation was augmented by adding CPA in combination with various CSFs, the colony type induced by CPA plus CSF was no different from that of CSF alone. Preincubation of bone marrow (BM) cells with CPA at 37 degrees C for 24 hours before using in clonal culture assay resulted in a marked colony enhancement. Furthermore, colony formation by 5-fluorouracil (5-FU)-treated marrow cells could be induced by granulocyte-macrophage (GM)-CSF plus CPA but not by GM-CSF alone. These results suggest that CPA may act on early developing hematopoietic stem cells to induce them to differentiate into more mature myeloid progenitor cells capable of responding to CSF stimulation. CPA was nondialyzable and stable under heat (56 degrees C for 30 minutes) and freeze/thawing (3 times). Its activity was acid-labile (pH 2.0) but relatively alkaline-resistant (pH 11.0). When treated with enzymes, CPA was sensitive to trypsin and bacterial protease but not to neuraminidase. In addition, the activity of CPA could be abrogated by anti-CPA antiserum but remained unchanged after treatment with antibodies to other murine hematopoietic synergizing/stimulating factors, including interleukin-1 (IL-1), IL-3, IL-4, IL-6, and stem cell factor (SCF).
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PMID:Cell source and biological characteristics of murine bone marrow-derived colony-promoting activity. 833 Jun 47

Stem cell factor (SCF), also known as mast cell growth factor, kit ligand, and steel factor, is the ligand for the tyrosine kinase receptor (SCFR) that is encoded by the c-kit proto-oncogene. We analyzed the effects of recombinant human SCF (r-hSCF, 5-50 micrograms/kg/day, injected subcutaneously) on mast cells and melanocytes in a phase I study of 10 patients with advanced breast carcinoma. A wheal and flare reaction developed at each r-hSCF injection site; by electron microscopy, most dermal mast cells at these sites exhibited extensive, anaphylactic-type degranulation. A 14-d course of r-hSCF significantly increased dermal mast cell density at sites distant to those injected with the cytokine and also increased both urinary levels of the major histamine metabolite, methyl-histamine, and serum levels of mast cell alpha-tryptase. Five subjects developed areas of persistent hyperpigmentation at r-hSCF injection sites; by light microscopy, these sites exhibited markedly increased epidermal melanization and increased numbers of melanocytes. The demonstration that r-hSCF can promote both the hyperplasia and the functional activation of human mast cells and melanocytes in vivo has implications for our understanding of the role of endogenous SCF in health and disease. These findings also indicate that the interaction between SCF and its receptor represents a potential therapeutic target for regulating the numbers and functional activity of both mast cells and cutaneous melanocytes.
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PMID:Recombinant human stem cell factor (kit ligand) promotes human mast cell and melanocyte hyperplasia and functional activation in vivo. 867 90

The present study sought to determine the expression of alpha- and beta-tryptase in in vitro differentiated human cord blood derived mast cells. We also analysed the glycosaminoglycan composition and the phenotype of the cells. The major protease in human mast cells is tryptase, and cDNAs for two different human tryptases have been characterized, the so-called alpha- and beta-tryptase. By reverse transcriptase-polymerase chain reaction (RT-PCR) we could show that stem cell factor (SCF)-dependent cord blood derived mast cells express both alpha- and beta-tryptase. Furthermore, the cells were stained with a monoclonal antibody (mAb) against tryptase, and the tryptase was enzymatically active cleaving the substrate Z-Gly-Pro-Arg- methoxy-2- naphthylamide (MNA). The majority of the cord blood derived mast cells could also be stained with mAbs against chymase, cathepsin G and CD68. They also expressed Kit/SCFR (CD117), CD13, CD29 and CD45 on the cell surface. The proteoglycan-derived polysaccharide composition of the cells was estimated to be 25-35% of heparin origin and 65-75% of chondroitin sulphate origin. Hence, the cord blood derived mast cells exhibit a phenotype in common with the so-called MCTC type of human mast cells.
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PMID:Stem cell factor-dependent human cord blood derived mast cells express alpha- and beta-tryptase, heparin and chondroitin sulphate. 869 Apr 66


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