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A D Befus

Publications and source records attributed to A D Befus.

At least 127 records · Page 7Linked to original sources
PubMed1982

Isolation and properties of mast cells from the small bowel lamina propria of the rat.

A method is described for the isolation of mast cells from the mucosa of the small intestine of rats infected with the nematode Nippostrongylus brasiliensis. The cells release histamine on challenge with IgE-directed ligands and calcium ionophores but, in contrast to rat peritoneal mast cells, are refractory to the action of basic secretagogues. The mucosal and peritoneal cells also differ markedly in their sensitivity to particular anti-allergic drugs. These results further emphasize the functional heterogeneity of mast cells from different sources.

Anaphylaxis↗
PubMed1982

Relationship between tissue sensitization and IgE antibody production in rats infected with the nematode, Nippostrongylus brasiliensis.

In Nippostrongylus brasiliensis rats, tracheal sensitivity to worm allergens developed prior to intestinal sensitivity and correlated with the early local synthesis of reaginic antibody in the mediastinal (bronchial) lymph nodes. Skin and intestinal sensitivity to worm allergens more nearly correlated with serum reaginic antibody and its synthesis by mesenteric lymph nodes and other tissues. Prostaglandins appeared to modulate intestinal responsiveness to worm allergens. Thus, local reagin synthesis and other microenvironmental factors influence local tissue sensitization and responsiveness to allergens.

Allergens↗
PubMed1982

Nippostrongylus brasiliensis infection in the rat: effects of surgical removal of Peyer's patches, mesenteric lymph nodes and spleen.

The influence of the surgical removal of Peyer's patches, mesenteric lymph nodes and spleen has been examined on the host response to Nippostrongylus brasiliensis infection in the rat. In animals subjected to these procedures, no effects were observed on whole blood or plasma histamine levels, peripheral blood leucocytosis or reaginic antibody levels, intestinal mast cell numbers or histamine content, nor on faecal egg output.

Animals↗
PubMed1982

Mucosal mast cells. I. Isolation and functional characteristics of rat intestinal mast cells.

We have developed a procedure for the dispersion of mast cells from the intestinal lamina propria (LP) and epithelium of rats infected with the intestinal nematode, Nippostrongylus brasiliensis. The dispersed cells are morphologically and histochemically similar to intestinal mucosal mast cells (MMC) in situ and are distinguishable from peritoneal mast cells (PMC). MMC derived from the LP or epithelium of parasitized animals secrete histamine in response to the specific parasite antigens as well as anti-IgE. Unlike PMC, these cells are unresponsive to the basic secretagogues 48/80 and bee venom peptide 401. Similarly, bee venom peptide 401 conjugated with dansyl chloride binds to PMC and mast cells in the thymus and intestinal serosa, but not to mast cells in or derived from the intestinal LP and epithelium. Studies on PMC treated by the intestinal cell isolation procedure show that the functional characteristics of the MMC cannot be solely attributed to the isolation procedure. Thus, MMC have been isolated and shown to be morphologically, histochemically, and functionally different from PMC, as suggested by previous in vivo studies of the normal intestine.

Animals↗
PubMed1982

Mucosal mast cells. II. Effects of anti-allergic compounds on histamine secretion by isolated intestinal mast cells.

Functional mast cells have been isolated from the lamina propria of the small intestine of rats infected with the nematode Nippostrongylus brasiliensis. The cells released histamine on challenge with specific antigen, anti-rat IgE, concanavalin A, and calcium ionophores but were less responsive than peritoneal mast cells (MMC) from the same animals. Intestinal mucosa mast cells (PMC) were refractory to the action of the basic secretagogues peptide 401 from bee venom and compound 48/80. The anti-allergic compounds disodium cromoglycate (less than or equal to 10(-3) M), AH 9679 (less than or equal to 10(-4) M), and theophylline (less than or equal to 10(-2)) did not inhibit antigen-induced histamine secretion by MMC, although these compounds were effective against PMC. In contrast, doxantrazole (10(-5) to 10(-3) M) inhibited the secretion of histamine from both MMC and PMC in a comparable dose-dependent fashion. Thus, we have established that mast cells from different sites are functionally heterogeneous not only in their response to various stimuli for histamine secretion, but also in their responses to different pharmacologic modulators of secretion. It cannot be assumed that anti-allergic compounds effective against mast cells in one tissue site or organ will be equally efficacious against mast cells in other sites. The extent of this functional heterogeneity must be established, and its investigation may provide new insights into the biochemical events involved in mast cell secretion.

Animals↗
PubMed1982

Impaired intestinal localization of mesenteric lymphoblasts associated with vitamin A deficiency and protein-calorie malnutrition.

We examined whether protein-calorie (PC) and vitamin A (VA) deficiencies altered the intestinal localization of mesenteric lymph node (MLN) lymphoblasts using an adoptive lymphocyte transfer method. MLN cells from donor rats were labelled in vitro with [125I]-deoxyuridine and injected i.v. into various recipients. Twenty-two to twenty-four hours after transfer of labelled cells prepared from PC-deficient donors, the percentage of radioactivity in the small intestine of normal recipients was two-thirds of that detected after transfer of cell obtained from normal donors. When donor cells were obtained from rats suffering both PC and VA malnourishment, this decrease was even greater, being only one-third of the normal donor cell control. Other experiments indicated that the defect in localization behaviour was associated with the donor blasts and not the recipient intestine. These findings suggest that defective localization in mucosal lymphoblasts may be a factor contributing to morbidity in malnourished populations.

Animals↗
PubMed1981

Basophil production III: relation of histamine to guinea pig basophil growth in vitro.

Histamine has been measured by an isotopic enzyme conversion assay in guinea pig bone marrow cultures under conditions which stimulate basophilopoiesis. A high degree of correlation was observed between histamine values and basophil counts in suspension cultures. Cultures of normal marrow with splenic conditioned medium (CM) prepared from spleen cells of ovalbumin (OA)-treated animals or coculture of marrow cells from these animals with autologous spleen cells demonstrated rises in histamine values which paralleled basophil counts, with a mean calculated histamine of 0.3 pg/basophil. Addition to marrow cells from OA-treated animals of autologous splenic T-lymphocytes or culture of normal marrow in the presence of CM derived from PHA-stimulated splenic T-lymphocytes caused in vitro increases in histamine significantly greater than when T-lymphocyte depleted spleen cells or CM derived from the latter were used, respectively (P less than 0.02). The presence of OA in marrow-spleen cultures significantly enhanced basophilopoiesis when whole or T-enriched, but not T-depleted, spleen fractions were used (P less than 0.02). The magnitude of in vitro increases in histamine over one week was 10-30 nanograms, accompanied by appropriate increases in basophils in CM-stimulated normal marrow cultures. From these data it can be concluded that histamine is an independent criterion of basophilopoiesis in vitro. An entirely new population of histamine-synthesizing cells appears to arise over 1 week in vitro under conditions of antigen or T-cell product stimulation.

Animals↗
PubMed1981

Selective localization of mesenteric lymphoblasts in mucosal tissues: effects of altering the number of donor lymphoblasts.

We have studied the effect of altering the numbers of lymphoblasts from the mesenteric lymph node (MLN) transferred into syngeneic female CBA/J mice on their distribution and abundance 24 hr later. The frequency of [3H]-thymidine-labelled donor MLN cells in the recipient small intestine and lungs was directly related to the numbers transferred. Of the donor MLN lymphoblasts in the small intestine, 62.5% +/- 0.9% were seen in the basal lamina propria, 32.5% +/- 0.9% in the villus lamina propria and 5% +/- 0.6% in the epithelium. Of the MLN lymphoblasts localizing in the lungs, 90% +/- 2.3% were in the parenchyma while 6.7% +/- 1.8% and 3.3% +/- 1.0% appeared in the bronchus-associated lymphoid tissue (BALT) and the bronchial epithelium, respectively. Although few peripheral lymph node (PLN)- derived lymphoblasts localized in the small intestine, the numbers of PLN lymphoblasts in the lungs were similar to those observed after transfer of comparable doses of MLN lymphoblasts. However, PLN Lymphoblasts were found only in the pulmonary parenchyma and did not appear in either BALT or bronchial epithelium. These data suggest that the number of MLN, but likely not PLN, lymphoblasts in the circulation, directly influences the numbers of lymphoblasts which localize in intestinal mucosa, BAlt and bronchial epithelium. Even at the highest doses of MLN lymphoblasts transferred we could not saturate the capacity of these tissues to accommodate MLN lymphoblasts nor was their intra-intestinal distribution altered.

Animals↗
PubMed1981

Thymic mast cell deficiency in avian muscular dystrophy.

In animals with hereditary muscular dystrophy there are thymic abnormalities which may be of etiological significance in the dystrophic process. This study investigated mast cell number and histamine levels in the thymus of normal and dystrophic chickens. For comparison, other lymphoid tissues, namely the spleen and the bursa of Fabricius, and non-lymphoid tissues including the comb and pectoralis major muscle, were similarly studied. Our results show that the thymus of dystrophic adult birds has a deficiency in both mast cell number and histamine content. In the bursa of Fabricius of dystrophic birds a significant elevation in histamine content (microgram/g) was attributed to the abnormally small size of this organ, rather than to an absolute mast cell increase. The deficiency in thymic mast cell number in dystrophic chickens may be significant in the postulated abnormal thymus-muscle interaction of the dystrophic process.

Animals↗
PubMed1980

Growth and differentiation in vitro of mast cells from mesenteric lymph nodes of Nippostrongylus brasiliensis-infected rats.

Intestinal mastocytosis begins to develop in rats, depending on the strain, at 14 (outbred Sprague-Dawley, SD) or 16 (inbred Lewis, L) days after infection with the nematode Nippostrongylus brasiliensis (Nippo). We have investigated in vitro mastopoiesis from mesenteric lymph node (MLN) cells cultured at various intervals post-infection, using a modified Marbrook liquid system. Greater increases in mast cells (MC) were observed in cultures of SD-MLN removed on day 14 after Nippo infection (IMLN-14) than from MLN removed from uninfected animals (NMLN): seven- to twenty-fold versus up to two-fold at 2 weeks and forty- to two hundred-fold versus up to twenty-fold at 4 weeks, respectively (P < 0.002). In contrast, similar differential increases in MC and histamine compared to uninfected controls, were demonstrated in 2 week cultures of MLN from L strain rats removed 17 (IMLN-17) and 20 (IMLN-20) but not 14 days after Nippo infection (P < 0.001). the presence of phytohaemagglutinin (PHA) in vitro was associated with enhanced MC differentiation from both IMLN-17 and IMLN-20, while worm antigen (Ag) stimulated mastopoiesis from IMLN-17, but suppressed the response from IMLN-20 (P < 0.02). Conditioned media (CM) prepared from unstimulated or PHA-stimulated IMLN-32 (i.e. removed 32 days after Nippo infection) caused significant mastopoiesis from NMLN in vitro when compared to no CM or Ag-stimulated CM (P < 0.01). Either MC precursors or cells which help MC differentiation exist in increased numbers in MLN of Nippo-infected rats. Mitogenic or antigenic stimulation modulates in vitro mastopoiesis, either directly or through soluble factors derivable from MLN cells. These in vitro methods can be utilized to understand further mechanisms of intestinal mastocytosis in the rat.

Animals↗
PubMed1980

Gut-associated lymphoid tissue in the chicken. I. Morphology, ontogeny, and some functional characteristics of Peyer's patches.

Lymphoid aggregates with many of the characteristics of mammalian Peyer's patches (PP) were identified in the chicken intestine. These chicken PP could not be seen with the naked eye at the time of hatching, but by 10 days of age, 1 or 2 PP were identified in 50% of the birds. Up to 16 wk of age, the numbers of PP increased to a maximum of 5 per animal and they were widely scattered in the intestine, apart from one that was regularly found about 5 to 10 cm anterior to the ileocecal junction. As the birds aged, the number of PP declined so that in older birds (58 wk) only a single PP was evident near the ileocecal junction. Chicken PP possess: a distinct lymphoepithelium with M cells and strong pinocytotic activity; follicles and a subepithelium zone and central zone similar to those of the cecal tonsil (CT). Studies with in ovo hormonal bursectomy and age-associated involution of PP suggested that the subepithelial zone is a B-dependent area and the central zone a T, or thymus-dependent region. These observations extend our knowledge of gut-associated lymphoid tissue (GALT) in the bird to include the bursa of Fabricius, CT, PP, and aggregates in the urodeum and proctodeum. They raise issues about the roles of chicken PP that may aid our understanding of the functions of mammalian GALT.

Animals↗
PubMed1979

Immunologically mediated intestinal mastocytosis in Nippostrongylus brasiliensis-infected rats.

To investigate mechanisms of mast-cell proliferation, we have utilized infection of Lewis rats with the intestinal nematode, Nippostrongylus brasiliensis, which induces a pronounced intestinal mast-cell hyperplasia. Adoptive transfer of 2 x 10(8) immune mesenteric lymph node cells (IMLN), collected 14 days post infection with 3000 third stage larvae (L3), into rats concurrently given 3000 L3 hastened the expected intestinal mastocytosis by up to 4-5 days. IMLN exhibited this mastopoietic activity in the presence but not in the absence of concurrent infection. Normal mesenteric lymph node cells did not show similar mastopoietic activity. Intestinal mastocytosis was delayed by sub-lethal irradiation (400 rad) but IMLN reconstituted the mast-cell response of such animals. The mastopoietic activity could not be attributed to worm antigen as antigen administered intravenously had no significant effect on mastocytosis and furthermore, antigen could not be detected in mastopoietically active IMLN suspensions used as a possible antigen source in passive cutaneous anaphylaxis tests. Immune serum (14 days post primary infection with 3000 L3) also hastened mastocytosis in infected rats, whereas normal serum did not. The IMLN may be an enriched source of intestinal mast cell precursors and, in addition, may contain a cell type(s) which regulates the differentiation and proliferation of such precursors.

Animals↗