Search PubMed⌕ Search

Biomedical subjects

A D Befus

Publications and source records attributed to A D Befus.

At least 91 records · Page 5Linked to original sources
PubMed1987

Human lung mast cells: distribution and abundance of histochemically distinct subpopulations.

Methods originally employed to demonstrate the heterogeneity of mast cells in the rat and more recently in the human intestine were used to study mast cell heterogeneity in the human bronchial mucosa and lung parenchyma. Thus, a quantitative survey of pulmonary mast cells using different fixation and staining procedures indicated that two distinct mast cell subpopulations (formalin-sensitive and formalin-resistant) are present and have distinct patterns of distribution and abundance. The findings are of potential clinical importance because histochemical heterogeneity may be a marker of functional mast cell differences in humans including differences in responsiveness to antiallergic drugs, as occurs in rats. The findings also indicate that conventional methods of fixation are likely to lead to a gross underestimation of total mast cell numbers.

Bronchi↗
PubMed1987

Reciprocal regulation of human basophil and eosinophil differentiation by separate T-cell-derived factors.

Basophil and eosinophil progenitors are present in human hemopoietic tissues, including cord blood. In the present studies, cord blood cultures demonstrating differentiation of basophils or eosinophils have been maintained for prolonged periods in the presence of conditioned medium from a human T-cell leukemia line (Mo-CM). Peak basophil counts and histamine levels were followed almost invariably by a second peak of eosinophils in vitro. Morphologic examination revealed the consistent presence of cells with mixed basophil-eosinophil granulation. Both basophil and eosinophil growth-stimulating activities were found in Mo-CM, were heat stable and nondialyzable, and could be partially separated from each other by a multistep procedure that included ion-exchange chromatography on DEAE-cellulose. Mixing experiments using separated basophil- and eosinophil-stimulating activities revealed that suppression of basophil growth was accompanied by reciprocal enhancement of eosinophil growth, a finding that could be confirmed on analysis of morphology of single colonies from cord blood progenitors in methylcellulose. These studies point to the existence of regulatory growth factors in Mo-CM that stimulate and/or inhibit the growth and differentiation of human basophils and eosinophils from a common, committed progenitor cell.

Basophils↗
PubMed1987

Nippostrongylus brasiliensis-induced depression of heterologous immune responses: effects of the histamine H2 receptor antagonist, cimetidine.

Both mucosal and systemic immune responses are depressed in mice infected with the nematode Nippostrongylus brasiliensis and this is correlated with a striking increase in the numbers of histamine-containing, mucosal-associated mast cells. As suppressor T cells bear histamine H2 receptors, we have used the H2 antagonist, cimetidine, to test whether histamine mediates N. brasiliensis-induced immunodepression. In uninfected mice, mitogenic responses to PHA and Con A were increased by treatment with cimetidine; in some experiments this treatment also increased antibody responses to a T-dependent antigen (TNP-BGG). By contrast, these T- and B-cell responses were markedly depressed in mice infected with N. brasiliensis, and cimetidine treatment did not alter this parasite-induced immunodepression. These results imply that although histamine can modulate immune responses in uninfected animals, it is not a major component of the immunoregulatory pathway induced by infection with N. brasiliensis.

Animals↗
PubMed1986

Intestinal mucosal mast cells from rats infected with Nippostrongylus brasiliensis contain protease-resistant chondroitin sulfate di-B proteoglycans.

Rats infected with the helminth Nippostrongylus brasiliensis were injected i.p. with 2 mCi of [35S] sulfate on days 13, 15, 17, and 19 after infection. The intestines were removed from animals on day 20 or 21 after infection, the intestinal cells were obtained by collagenase treatment and mechanical dispersion of the tissue, and the 35S-labeled mucosal mast cells (MMC) were enriched to 60 to 65% purity by Percoll centrifugation. The cell-associated 35S-labeled proteoglycans were extracted from the MMC-enriched cell preparation by the addition of detergent and 4 M guanidine HCl and were partially purified by density gradient centrifugation. The isolated proteoglycans were of approximately 150,000 m.w., were resistant to pronase degradation, and contained highly sulfated chondroitin sulfate side chains. Analysis by high-performance liquid chromatography of chondroitinase ABC-treated 35S-labeled proteoglycans from these rat MMC revealed that the chondroitin sulfate chains consisted predominantly of disaccharides with the disulfated di-B structure (IdUA-2SO4----GalNAc-4SO4) and disaccharides with the monosulfated A structure (G1cUA----GalNAc-4SO4). The ratio of disaccharides of the di-B to A structure ranged from 0.4 to 1.6 in three experiments. Small amounts of chondroitin sulfate E disaccharides (GlcUA----GalNAc-4,6-diSO4) were also detected in the chondroitinase ABC digests of the purified rat MMC proteoglycans, but no nitrous acid-susceptible heparin/heparan sulfate glycosaminoglycans were detected. The presence in normal mammalian cells of chondroitin sulfate proteoglycans that contain such a high percentage of the unusual disulfated di-B disaccharide has not been previously reported. The rat intestinal MMC proteoglycans are the first chondroitin sulfate proteoglycans that have been isolated from an enriched population of normal mast cells. They are homologous to the chondroitin sulfate-rich proteoglycans of the transformed rat basophilic leukemia-1 cell and the cultured interleukin 3-dependent mouse bone marrow-derived mast cell, in that these chondroitin sulfate proteoglycans as well as rat serosal mast cell heparin proteoglycans are all highly sulfated, protease-resistant proteoglycans.

Animals↗
PubMed1986

Detection and characterization of cytotoxic T lymphocyte precursors in the murine intestinal intraepithelial leukocyte population.

Highly purified preparations of intraepithelial leukocytes (IEL) were obtained from the small intestinal mucosa. Leukocytes from the lamina propria (LPL) were isolated and phenotypically compared with IEL to verify that IEL were minimally contaminated by LPL. Because approximately 80% of IEL expressed the Lyt-2 antigen usually associated with cytotoxic/suppressor T lymphocytes, we wished to determine if precursors for cytotoxic T cells were present in this population. In order to generate cytotoxic cells, IEL and spleen cells from CBA/J mice (H-2k) were co-cultured with irradiated allogeneic spleen cells (H-2d or H-2b) in a one-way mixed leukocyte reaction (MLR). Four to six days later, the cultured cells were assayed against 51Cr-labeled H-2d or H-2b tumor or Con A-stimulated lymphoblast target cells, and the specificity of alloantigen-stimulated IEL and spleen cells was compared. The cytotoxic cells derived from both tissues displayed antigen-specific lysis of the allogeneic targets. Treatment of effector cells, generated from intraepithelial or splenic precursors, with monoclonal antibodies against Thy-1.2, Lyt-1.1, or Lyt-2.1 antigens plus complement, decreased cytotoxicity 85 to 100%, even though only 20 to 50% of the cells were lysed. The alloantigen specificity and surface antigen phenotype of the cultured IEL cells were identical to those of spleen cells and allowed us to conclude that IEL contained a cytotoxic T lymphocyte precursor (CTLp). Further characterization showed that, like spleen, the intraepithelial CTLp was Thy-1+ and Lyt-1+ and their sedimentation velocity was the same but differed from intraepithelial natural killer cells. Although 80% of IEL were Lyt-2+, the frequency of CTLp in the IEL population was estimated to be threefold to fivefold lower than in spleen, and the Lyt-2+ cells were shown not to be an enriched source of CTLp. Thus, the function of the majority of the IEL is still not known. However, there exists within this population CTLp, which may be capable of being stimulated with luminal antigens.

Animals↗
PubMed1986

Intraepithelial leukocytes contain a unique subpopulation of NK-like cytotoxic cells active in the defense of gut epithelium to enteric murine coronavirus.

Initially the intraepithelial leukocytes (IEL) of specific pathogen free (SPF) mice were compared with those of mice held without isolation and were found to differ markedly in total number and distribution of cell surface antigens. The IEL from SPF mice expressed significantly less Thy-1, Lyt-1, and Lyt-2 antigens than their conventional counterparts. The local cell-mediated immune response of mucosal lymphocytes to an enteric murine coronavirus (MHV-Y) was studied in inbred strains of naive SPF mice. A potent in vitro cytotoxic activity was demonstrated by mucosal leukocytes, especially IEL, and spleen cells for MHV-Y-infected syngeneic and allogeneic target cells. The cytotoxicity was not restricted by the major histocompatibility complex. Targets infected with Pichinde virus, an enveloped nonenterotropic virus, were not lysed by these cells. The phenotype of the IEL effector cell was asialo GM1+, Thy-1-, Lyt-1-, Lyt-2-. This cell represents a small subpopulation of the total IEL. After the in vivo administration of anti-asialo GM1 sera, the virus-specific cytotoxic function of the IEL was markedly diminished in in vitro assays, and there was enhanced persistence of virus in gut tissues in vivo. The IEL effector population is defined as a natural killer-like cell that appears to be active in the defense of the gut epithelium to a murine enteric coronavirus.

Animals↗
PubMed1986

Intestinal immunity and inflammation: recent progress.

The previous sections illustrate that we are still defining (a) which sets of lymphoid cells are present in the intestine and which are not, (b) which sets are peculiar to the intestine, and (c) how the sets that are there function in the intestinal microenvironment. An understanding of the latter point is going to require knowledge of how these sets communicate with and regulate one another via cell surface molecules such as MHC class I and class II molecules, and via soluble mediators or lymphokines. The recent advances in various technologies make this a particularly exciting time in this field because the tools are now available to address and answer some of these basic and important questions in mucosal immunology. At the same time these advances hold great promise for our eventual understanding of chronic inflammatory diseases of the intestine. As was mentioned at the outset, the immune system has considerable power for both protection and destruction. It remains a puzzle how this latter potential is contained and controlled in the intestine of most individuals, such that they do not have inflammatory disease even in the setting of intense stimulation by substances, such as endotoxin, that are phlogistic elsewhere in the body. An answer to the question of why everyone does not have intestinal inflammation could provide new insights into the mechanisms involved in chronic intestinal inflammatory diseases. The recent advances just detailed, as well as others sure to come, suggest that it is only a matter of time before such questions are answered.

Animals↗
PubMed1986

Mast cell responses to helminth infection.

Mast cells have been suggested to be major effector cells in the immune response to infection with helminths. It is now clear, however, that mast cells are heterogeneous and have a diversity of important functions. In this review, Timothy Lee, Mark Swieter and Dean Befus point out that much of the confusion about the role of mast cells in immunity stems from methods and interpretations which are inadequate for the diversity of roles played by these cells in host responses to parasites. Classical histochemistry may fail to reveal active mast cells, and studies using chemical antagonists are difficult to interpret until we know more about the action of the drugs. The authors show that current research is extending our knowledge of mast cell heterogeneity, and helping to define the powerful array of mediators that they can use to orchestrate the immune response to helminth infections.

Journal Article↗
PubMed1986

Basophilic cell progenitors, nasal metachromatic cells, and peripheral blood basophils in ragweed-allergic patients.

Circulating hematopoietic progenitor cells giving rise to colonies containing basophilic cells (basophilic cell colony-forming units in culture [CFU-c]), nasal epithelial metachromatic cells (basophils and/or mast cells) (NMC), and blood basophils were enumerated before, during, and after a ragweed-pollen season in patients with ragweed hayfever and patients with perennial allergic rhinitis who were not ragweed allergic. In the patients with seasonal hay fever, the following was observed: basophilic cell CFU-c, measured as basophilic cell or histamine-containing colonies, were significantly reduced during the ragweed season compared to before (p less than 0.005) or after (p less than 0.025) the season in the ragweed-allergic group only. Conversely, peripheral blood basophils were higher during the ragweed season than before or after (p less than 0.001) in the ragweed-allergic group, whereas the number of NMC was higher during the season than before the season in this group (p less than 0.05). There were no such changes during the season in the group of patients with perennial allergic rhinitis. The observed seasonal changes in both NMC and circulating basophilic cell CFU-c are discussed in the context of lineage relationships among metachromatic cell types.

Basophils↗
PubMed1986

Effect of beclomethasone dipropionate on nasal metachromatic cell sub-populations.

The effect has been investigated of local administration of beclomethasone dipropionate (BDP) on cell numbers of nasal epithelial metachromatic cell (NMC) sub-populations. Twenty-one patients with perennial allergic rhinitis were studied in four groups according to the duration of treatment or after treatment with BDP. Nasal scrapings were taken after 1 week (Group 1) or 2 weeks (Group 2) of BDP treatment, or after discontinuing BDP for 1 week (Group 3) or 2 weeks (Group 4). Cells were fixed with Mota's lead acetate or 10% buffered formalin followed by toluidine blue staining to count the number of NMC and to classify these according to morphological sub-types (basophils or mast cells). Formalin-sensitive mast cells and basophils in nasal scrapings were reduced more than formalin-resistant mast cells with BDP treatment. Formalin-sensitive mast cells were also more prompt to recover from BDP than formalin-resistant mast cells. The results suggest that the formalin-sensitive NMC is a sub-population of cells which responds to BDP treatment in allergic rhinitis.

Administration, Topical↗
PubMed1986

Mast cell heterogeneity: effect of anti-allergic compounds on neuropeptide-induced histamine release.

Increasing evidence suggests that neuropeptides may be important stimuli for mast cell secretion. Neuropeptide-induced histamine secretion from rat mast cells was inhibited by a variety of clinical and experimental antiallergic agents. The profile of responsiveness to this panel of drugs exhibited by peritoneal (PMC) and intestinal mucosal mast cells (IMC) was similar to that previously reported when histamine release was immunologically induced. Thus, cromoglycate, theophylline and Ro 22-3747 inhibited peptide-induced secretion from PMC but not from IMC. In contrast, doxantrazole was effective against PMC and IMC. Differences between IMC and PMC could not be attributed to the IMC isolation procedure. The results confirm the heterogeneity of responsiveness to antiallergic drugs exhibited by these mast cell subpopulations and indicate that it is not limited to immunologically induced secretion but also occurs when a neuropeptide is the secretory stimulus.

Animals↗
PubMed1986

Functional characterization of mast cells generated in vitro from the mesenteric lymph node of rats infected with Nippostrongylus brasiliensis.

We have examined the biochemical and functional characteristics of mast cells grown in tissue culture from the mesenteric lymph node (MLN) of rats infected with the nematode Nippostrongylus brasiliensis and compared them with mast cells isolated from the small intestinal mucosa and peritoneal cavity of infected animals. Cultured mast cells (MC) and isolated intestinal mucosal mast cells (MMC) had a similar histamine content, and both contained type II protease (RMCP II) which was absent from peritoneal mast cells (PMC). PMC, MMC and cultured MC each responded to immunologically induced histamine secretion, but MMC and cultured MC were hyporesponsive to calcium ionophores and unresponsive to widely used PMC secretagogues including compound 48/80 and bee venom peptide 401. MMC and cultured MC also differed from PMC in their lack of responsiveness to the anti-allergic agent disodium cromoglycate. Thus, MC cultured from the MLN are distinct from PMC but have a biochemical and functional phenotype similar to that of intestinal MMC.

Animals↗
PubMed1985

Murine intestinal intraepithelial lymphocytes I. Relationship of a novel Thy-1-,Lyt-1-,Lyt-2+, granulated subpopulation to natural killer cells and mast cells.

Highly purified populations of intraepithelial lymphocytes (IEL) were obtained from the murine small intestine. We found that 84% of IEL expressed Lyt-2 and that 45-55% possessed the unique phenotype, Thy-1-,Lyt-1-,Lyt-2+. Sixty percent of IEL had granules in their cytoplasm and thus resembled the large granulated lymphocytes associated with natural killer (NK) activity. However, less than 15% of IEL had NK activity in a 6-h assay. This activity resided in a subpopulation of Lyt-2- lymphocytes, leaving a large population of Thy-1-,Lyt-1-,Lyt-2+ granulated cells (45-55% of IEL) with unknown function. Sensitive radioenzymic assays for histamine showed that IEL from healthy CBA mice do not contain this amine. IgE-binding assays revealed that IEL, unlike mast cells, do not carry high-affinity receptors for IgE. Thus, only a small percentage of granulated IEL (less than 15%) possess NK activity, whereas 45-55% of IEL have granules, lack typical characteristics of mast cells, express the unique antigenic phenotype, Thy-1-,Lyt-1-,Lyt-2+ and have unknown function.

Animals↗
PubMed1985

Murine intestinal intraepithelial lymphocytes II. Comparison of freshly isolated and cultured intraepithelial lymphocytes.

Highly enriched preparations of intraepithelial lymphocytes (IEL) containing a large subpopulation of granulated cells were isolated from the murine small intestinal mucosa. We cultured IEL in media containing interleukin 2 (growth media conditioned with 20% concanavalin A supernatant; Con A CM) or mast cell growth factor(s) (growth media conditioned with 40% WEHI-3 supernatant; WEHI CM) and compared the physical and functional properties of the cultured cells to freshly isolated IEL. IEL cultured in Con A CM developed enhanced cytotoxicity against YAC-1, compared to freshly isolated IEL, and spontaneous cytotoxicity for P815 targets. Most of these cultured cells were Thy-1+ Lyt-1- Lyt-2+, and contained cytoplasmic granules similar to those seen in electron photomicrographs of other cytotoxic cell populations. IEL cultured in WEHI CM gave rise to cells that morphologically resembled mast cells. Unlike freshly isolated IEL, the cells stained metachromatically, contained 200-450 ng of histamine/10(6) cells and expressed high-affinity receptors for IgE. Our data clearly show that, although IEL do not themselves have physical characteristics of mast cells, they do contain mast cell precursors. In addition, IEL grown in the presence of T cell growth factors give rise to an activated cytotoxic cell population which is mostly granulated and Thy-1+ Lyt-1- Lyt-2+.

Animals↗
PubMed1985

Multinucleate giant cells in murine and rat lungs during Nippostrongylus brasiliensis infections. A study of the kinetics of the response in vivo, cytochemistry, IgG- and C3-mediated functions.

The cytochemical and functional characteristics of broncho-alveolar multinucleate giant cells and the kinetics of the giant cell response in the lungs of mice and rats during Nippostrongylus brasiliensis infection were studied. Primary infections resulted in significantly increased numbers of recoverable giant cells for up to 30 and 50 days in rats and mice, respectively. During secondary infections in the rat the giant cell response was more rapid and greater in magnitude than in a primary infection, suggesting that it was immunologically mediated. The giant cells displayed decreased C3- and IgG-dependent binding or phagocytic potential compared with mononucleate alveolar macrophages. Fusion of mononucleate alveolar macrophages into giant cells may therefore compromise complement and antibody dependent helminthocidal activity of these cells.

Animals↗