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Biomedical subjects

D D Metcalfe

Publications and source records attributed to D D Metcalfe.

At least 217 records · Page 12Linked to original sources
PubMed1985

The histologic and functional characterization of enzymatically dispersed intestinal mast cells of nonhuman primates: effects of secretagogues and anti-allergic drugs on histamine secretion.

Despite the apparent involvement of gastrointestinal mast cells in hypersensitivity reactions in the mucosa, remarkably little information is available concerning the characteristics of these cells from man and higher animals. To study the characteristics of gastrointestinal mast cells from nonhuman primates, a previously described technique which uses a combination of mechanical and enzymatic methods to obtain mast cells from the tissues of rodents required modification to permit the successful dispersion of normal gastrointestinal tissues of higher animals. This modified procedure, as described in this report, appears to be relatively selective for mast cells located in the mucosal site, and typically yields ca 9 X 10(5) mast cells per gram of tissue. The mucosal mast cells obtained comprised ca 2% of the total nucleated cells, contained approximately 1 pg of histamine per cell, and stained metachromatically with toluidine blue only at low pH. The cells exhibited a dose-dependent release of histamine on challenge with goat anti-human IgE or the ionophores A23187 and Br-x537A but were refractory to the action of compound 48/80. IgE-mediated histamine release from monkey intestinal mast cells differed from that observed from rat intestinal mast cells in that release was inhibited not only by quercetin but also by theophylline. Disodium cromoglycate gave variable results. The data indicate that viable nonhuman primate mucosal mast cells can be obtained for study, and that these cells, although sharing some characteristics of mucosal mast cells from lower species, have distinct and unique properties. The availability of this nonhuman primate model for the study of mast cell function in higher animals should contribute to the understanding of mast cell-mediated diseases in man.

Animals↗
PubMed1985

Interactions between food antigens and the immune system in the pathogenesis of gastrointestinal diseases.

This review details the evidence that interactions between food antigens and the immune system may play a role in the pathogenesis of several gastrointestinal diseases. In immediate hypersensitivity reactions to foods involving the gastrointestinal system, in milk-induced gastrointestinal disease in infants and children, and in some forms of hypereosinophilic gastroenteritis, the evidence for the participation of food antigens is extensive. Gluten-induced enteropathy and some forms of dermatitis herpetiformis are also induced by defined food proteins where the response is specific and characteristic. The role of food antigens in the pathogenesis of inflammatory bowel disease is unclear, and warrants further studies.

Animals↗
PubMed1985

Biochemical and microscopic evidence for the internalization and degradation of heparin-containing mast cell granules by bovine endothelial cells.

Incubation of [35S]heparin-containing mast cell granules with cultured bovine endothelial cells was followed by the appearance of 35S-granule-associated radioactivity within the endothelial cells and a decrease in radioactivity in the extracellular fluid. These changes occurred during the first 24 hours of incubation and suggested ingestion of the mast cell granules by the endothelial cells. Periodic electron microscopic examination of the monolayers confirmed this hypothesis by demonstrating apposition of the granules to the plasmalemma of endothelial cells, which was followed by the engulfment of the granules by cytoplasmic projections. Under light microscopic examination, mast cell granules within endothelial cells then appeared to undergo degradation. The degradation of [35S]heparin in mast cell granules was demonstrated by a decrease in the amount of intracellular [35S]heparin proteoglycan after 24 hours and the appearance of free [35S]sulfate in the extracellular compartment. Intact endothelial cells were more efficient at degrading [35S]heparin than were cell lysates or cell supernatants. These data provide evidence of the ability of endothelial cells to ingest mast cell granules and degrade native heparin that is presented as a part of the mast cell granule.

Animals↗
PubMed1984

Mast cell heterogeneity: evidence and implications.

Mast cells and basophils play a fundamental role in the pathogenesis of allergic disease, although their physiologic role is largely unknown. A large body of evidence now indicates that the properties of mast cells are dependent on the tissue and species from which they are derived. Such mast cell heterogeneity encompasses differences in morphology, development, cytochemistry, and function. The evidence for such heterogeneity, and some of its clinical implications, is discussed.

Animals↗
PubMed1984

Typical and atypical mast cells of the rat gastrointestinal system: distribution and correlation with tissue histamine.

Mast cells and histamine are present throughout the rat gastrointestinal system. Typical mast cells, differentiated from atypical mast cells by morphology, staining characteristics, and response to Compound 48/80, were the only mast cell type identified by histology in the cheek, tongue, esophagus, and nonglandular stomach. Atypical mast cells were found in large numbers in the glandular stomach, small and large intestine, and cecum, where they outnumbered typical mast cells by up to 20:1. Gastrointestinal histamine levels varied from 2.6 to 19.3 ng/mg in all tissues surveyed except for the glandular stomach, which contained 26 ng/mg. The amount of histamine per typical mast cell was estimated to be approximately 1.29 picograms; atypical mast cells contained less than 0.15 picograms per cell. Parenteral administration of Compound 48/80 resulted in the degranulation of typical mast cells, but not atypical mast cells, as determined by a fall both in typical mast cell number and a decrease in tissue histamine in areas rich in typical mast cells. These results indicate that striking regional differences in mast cell distribution and tissue histamine levels exist in the rat gastrointestinal system.

Animals↗
PubMed1984

Histamine release from the cultured mouse mast cell line PT18 in response to immunologic and non-immunologic stimuli.

Cultured mouse mast cells that are dependent on spleen-derived factors for their proliferation and maintenance have been shown rapidly to release histamine in response to immunologic stimuli, concanavalin A, and ionophores A23187 and Br-x537A. These cells did not, however, release histamine when treated with compound 48/80 or adenosine 5'-triphosphate. Immunologically mediated histamine release was inhibited by theophylline and quercetin, but not by disodium cromoglycate. The results presented here are discussed in terms of the possible relationship of this cell line to mucosal mast cells.

Adenosine Triphosphate↗
PubMed1984

Mast cell mediators with emphasis on intestinal mast cells.

Mast cells occur throughout most tissues although they are more prevalent in areas which come into contact with the external environment such as the skin, lungs, and gastrointestinal tract. The physiologic role of this cell is not known; however, it has a recognized pathophysiologic role as an effector cell in immediate hypersensitivity reactions. Such mast cells, when activated by either immunologic or non-immunologic stimuli, both release and generate chemical mediators such as histamine and leukotrienes which then act on surrounding tissues. Depending upon the site of mast cell degranulation, a variety of clinical findings ensue. For example, mast cell degranulation in the lungs may lead to wheezing, while mast cell degranulation in the gastrointestinal tract may lead to vomiting and diarrhea. It is now recognized that not all mast cells are identical. The best example of this mast cell heterogeneity is found in the gastrointestinal tract. There is evidence that certain gastrointestinal mast cells both contain and generate mediators either distinct from or differing in quantity from those of mast cells found at other sites. Such observations suggest that a knowledge of these differences is required to understand gastrointestinal diseases in which mast cell activation plays a part.

Aging↗
PubMed1984

Biochemical and functional characterization of proteoglycans isolated from basophils of patients with chronic myelogenous leukemia.

Human basophils were obtained from three donors with myelogenous leukemia. Proteoglycans were labeled by using [35S]sulfate as precursor and were extracted in 1 M NaCl with protease inhibitors to preserve their native structure. [35S]proteoglycans filtered on Sepharose 4B with an average m.w. similar to that of a rat heparin proteoglycan that has an estimated m.w. of 750,000. The [35S]glycosaminoglycan side chains filtered with an average m.w. slightly smaller than a 60,000-m.w. glycosaminoglycan marker. The [35S]glycosaminoglycans were resistant to heparinase and susceptible to degradation by chondroitin AC lyase and chondroitin ABC lyase. The intact [35S]glycosaminoglycans chromatographed on DEAE Sepharose as a single peak eluting just before an internal heparin marker. These findings indicate that the [35S]glycosaminoglycans were made up only of chondroitin sulfates. No heparin was identified. The chondroitin sulfate disaccharides that resulted from the action of chondroitin ABC lyase on the basophil glycosaminoglycans consisted of 92% delta Di-4S, 6% delta Di-6S, and 2% disulfated disaccharides. The [35S]chondroitin sulfate proteoglycans were susceptible to cleavage with proteases and could be shown to be released intact from basophils during degranulation initiated by the calcium ionophore A23187. The basophil proteoglycans and glycosaminoglycans were capable of binding histamine in water, but not in phosphate-buffered saline, and had no anticoagulant activity.

Basophils↗
PubMed1984

Patterns of skeletal scintigraphy and their relationship to plasma and urinary histamine levels in systemic mastocytosis.

Scintigraphic findings in ten cases of systemic mastocytosis are described. Four radionuclide bone patterns were noted: normal, unifocal, multifocal, and diffuse. Compared with radiographic surveys, bone images were better able to show the widespread skeletal involvement in patients with diffuse disease, and to detect a greater number of focal lesions. Serum calcium, phosphorus, and bone-derived alkaline phosphatase, as well as urinary calcium, phosphorus, and hydroxyproline levels, were usually within normal limits even when the bone scintigrams were clearly abnormal. Plasma and urinary histamine levels were highest in patients whose bone images detected widespread skeletal involvement. In systemic mastocytosis, not only does scintigraphy document active bone disease more effectively than laboratory studies of bone metabolism and radiographs of bone, but it also appears to reflect the general severity of the disease process.

Adult↗
PubMed1984

An association between susceptibility to experimental autoimmune uveitis and choroidal mast cell numbers.

An association was found in rats of different strains between the susceptibility to EAU and the number of mast cells in the choroid of the eye. High responder rats (Lewis, CAR) had strikingly more choroidal mast cells than the low responder BN animals, whereas intermediate numbers of mast cells were found in the F1 hybrids of Lewis and BN (LBNF), which exhibited an average level of susceptibility to EAU. LeR rats, derived from the Lewis strain, developed EAU only when treated with B. pertussis, and their number of choroidal mast cells was only about 1/5 of that found in the Lewis rats. Unlike the differences in the number of choroidal mast cells, small variations were found in the skin mast cell numbers of the tested rats. It is proposed that the number of local mast cells may be one mechanism by which the susceptibility to an organ-specific autoimmune disease is genetically regulated.

Animals↗
PubMed1984

Glycosaminoglycan profiles in cloned granulated lymphocytes with natural killer function and in cultured mast cells: their potential use as biochemical markers.

Proteoglycans from three cloned, granulated lymphocyte cell lines with natural killer (NK) function (NKB61A2, HY-3, H-1) and one mast cell line (PT-18) were labeled with [35S]sulfate. [35S]proteoglycans were extracted in 1 M NaCl with protease inhibitors to preserve their native structure and were separated from unincorporated [35S]sulfate by Sephadex G-25 chromatography. [35S]proteoglycans from all four cell lines were chromatographed over Sepharose 4B and were found to have a similar range of m.w. The [35S]glycosaminoglycans from each cell line were then separated from parent proteoglycans by treatment with 0.5 M NaOH. The [35S]glycosaminoglycans from the three lymphocyte cell lines exhibited a similar m.w. as assessed by Sepharose 4B gel filtration, whereas the [35S]glycosaminoglycans from the mast cell line chromatographed as a smaller m.w. molecule. [35S )glycosaminoglycan charge characteristics were evaluated with DEAE C1-6B ion exchange chromatography. The consistency of the elution patterns was determined by using [35S]glycosaminoglycans obtained from radiolabelings of each cell line separated by 6 mo in culture. Each NK lymphocyte cell line reproducibly produced two distinct [35S]glycosaminoglycan chains that eluted in two regions well before the commercial heparin marker. The proportions of each chain were dependent upon the specific cell line. The mast cell line produced a single [35S]glycosaminoglycan chain, which eluted overlapping the internal commercial heparin marker, consistent with its higher charge characteristics. [35S]glycosaminoglycans from all cell lines were identified as chondroitin sulfates with the use of specific polysaccharidases. The NK lymphocyte glycosaminoglycans contained chondroitin 4-sulfate disaccharides. The mast cell glycosaminoglycans contained oversulfated disaccharides and chondroitin 4-sulfate disaccharides. Thus, each granulated NK lymphocyte cell line produced chondroitin sulfate glycosaminoglycans that were characteristic of that cell line and of different composition and less charge than those produced by cultured mast cells. These findings demonstrate that glycosaminoglycan profiles are useful biochemical markers in the characterization of diverse granulated cell lines including NK lymphocytes and mast cells.

Animals↗
PubMed1983

An avidin--biotin microELISA for rapid measurement of total and allergen-specific human IgE.

This paper describes an improved microtiter solid-phase enzyme immunoassay for the determination of total and allergen-specific human IgE. This assay technique is unique in its use of the avidin-biotin interaction to increase sensitivity. The avidin-biotin microtiter enzyme-linked immunosorbant assay (AB-microELISA) was performed in polyvinyl chloride microtiter plates using biotinylated anti-IgE and horseradish peroxidase (HRP)-avidin conjugate. This AB-microELISA technique enabled the quantitation of human serum IgE in the range of 0.1-5 ng/ml (10-500 pg/test) in less than 3 h. Total serum IgE, whether measured by the AB-microELISA or the paper radioimmunosorbant test (PRIST) was similar (correlation coefficient, r = 0.92). Further, the presence or absence of positive skin tests to 7 specific allergens determined in serum donors generally agreed with the presence or absence of allergen-specific IgE in their sera as measured by the AB-microELISA. The quantity of short ragweed allergen-specific IgE as determined by the AB-microELISA agreed with values obtained by the radioimmunosorbant test (RAST) (correlation coefficient, r = 0.89). No significant interference by ragweed-specific IgG (blocking antibody) was observed in the quantitation of allergen-specific IgE. The AB-microELISA is not only rapid and inexpensive, but also more sensitive than other published ELISA procedures and comparable to solid-phase radioimmunoassays in the quantitation of total and allergen-specific IgE.

Allergens↗
PubMed1983

Effector cell heterogeneity in immediate hypersensitivity reactions.

Histologic heterogeneity in the basophil and mast cell populations has been apparent for many years. The advent of tissue culture and cell separation procedures has now made it possible to explore distinct populations of basophils and mast cells, as should be evident from this review. In fact, the logical extension of such technology is the requirement that cell preparations used in exploring basophil and mast cell function be carefully defined to permit comparison of data from one laboratory to another. While this is a practical application of the knowledge of the characteristics of heterogeneity, the implications for future developments in the understanding of basophil and mast cell function are more theoretical. While both basophils and mast cells respond to degranulating stimuli and antiallergic compounds in a similar fashion, as a rule, this review has noted several exceptions including the failure of disodium cromoglycate to prevent rat mucosal mast cell degranulation induced by immunologic stimuli. Such observations suggest that the ability of given drugs to inhibit allergic responses in one target organ and not in another may be due in part to differing mast cell responses. This hypothesis can be extended to variation in response among infants, children, and adults to such drugs as antihistamines. Furthermore, the variety of symptoms seen in individuals may be a reflection of differing responses of those individuals' mast cells from organ to organ. For instance, one subject with ragweed sensitivity might express this sensitivity as asthma, and a second subject with ragweed sensitivity might express this sensitivity as rhinitis. This would depend upon the ability of their pulmonary and upper airway mast cells to bind ragweed-specific IgE, degranulate to IgE-mediated stimuli, or to be regulated by intrinsic control mechanisms. Of a yet more speculative nature is the attempt to discern the basis for basophil, and particularly mast cell, heterogeneity. The function of the mast cell is unknown, but theories include the rejection of parasites; regulation and repair of connective tissue; regulation of the microvasculature; regulation of gastric acid secretion; limitation of delayed hypersensitivity reactions; and detoxification of surrounding tissues. Any or all of these theories may be correct, however, such a diversity of possible biologic roles for the mast cell suggests that mast cell subpopulations may have highly specialized functions reflected in stimuli that lead to their proliferation, their response to degranulating stimuli, and their mediator content.(ABSTRACT TRUNCATED AT 400 WORDS)

Anaphylaxis↗