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Biomedical subjects

M C Jamur

Publications and source records attributed to M C Jamur.

At least 19 recordsLinked to original sources
PubMed2005

Ultrasonically nebulized distilled water prevents exogenous histamine hyperreactivity in Toxocara canis-infected mice.

OBJECTIVE: This study examines the effect of ultrasonically nebulized distilled water inhalation on the systemic histamine hyperreactivity of Toxocara canis-infected mice. METHODS: Uninfected and T. canis-infected mice received an intravenous sublethal dose of histamine and lethality rates were documented. At 24 days post infection, infected mice received ultrasonically nebulized distilled water inhalation for 1 h. Twenty-four hours later histamine levels were determined in bronchoalveolar lavage fluid as well as histamine lethality and toluidine blue-stained mast cell number in the lung. RESULTS: T. canis-infected mice showed increased lethality after exposure to histamine in comparison to uninfected mice. Ultrasonically nebulized distilled water inhalation prevented histamine-induced lethality and reduced toluidine blue-stained mast cell numbers in the lung. CONCLUSIONS: The correlation between decreases in stained mast cells in the lung after ultrasonically nebulized distilled water inhalation and inhibition of histamine-induced lethality in these animals suggests participation of mast cells in the phenomenon and could be helpful in understanding the mechanisms of hyperreactivity during helminth parasite infections.

Anaphylaxis↗
PubMed2003

Differential expression of integrin subunits on adherent and nonadherent mast cells.

Mast cell progenitors arise in bone marrow and then migrate to peripheral tissues where they mature. It is presumed that integrin receptors are involved in their migration and homing. In the present study, the expression of various integrin subunits was investigated in three systems of adherent and nonadherent mast cells. Mesentery mast cells, freshly isolated bone marrow-derived mast cells (BMMC) and RBL-2H3 cells grown attached to tissue culture flasks are all adherent mast cells and peritoneal mast cells, and cultured BMMC and RBL-2H3 cells grown in suspension represent nonadherent mast cell populations. Pure populations of mast cells were immunomagnetically isolated from bone marrow, mesentery and peritoneal lavage using the mast cell-specific monoclonal antibody AA4. By immunomicroscopy, we could demonstrate that all of these mast cells expressed alpha 4, alpha 5, alpha 6, beta 1 and beta 7 integrin subunits. The expression of the alpha 4 integrin subunit was 25% higher in freshly isolated mesentery mast cells and BMMC. Consistent with the results obtained by immunomicroscopy, mesentery mast cells expressed 65% more mRNA for the alpha 4 integrin subunit than peritoneal mast cells. In vitro studies were also conducted using the rat mast cell line RBL-2H3. RBL-2H3 cells grown attached to the tissue culture flasks or as suspension cultures expressed the same integrin subunits identified in bone marrow, mesenteric and peritoneal mast cells ex vivo. Similarly, the expression of alpha 4 integrin was higher in adherent cells. Therefore, alpha 4 integrins may play a critical role in the anchorage of mast cells to the extracellular matrix in bone marrow and in peripheral tissues.

Animals↗
PubMed2003

Mast cell degranulation induced by lectins: effect on neutrophil recruitment.

The mammalian lectin macrophage-derived neutrophil chemotactic factor (MNCF) and the plant lectin KM+ were characterized for their ability to activate and degranulate mast cells. The association between mast cell activation and the induction of neutrophil migration was also investigated. Incubation of rat peritoneal mast cells with these lectins resulted in degranulation and mediator release. By confocal microscopy, both lectins were evenly distributed on the cell surface. MNCF activated RBL-2H3 mast cells only if the cells had been sensitized with IgE. KM+ was able to activate either unsensitized or IgE sensitized RBL-2H3 cells. In microplate assays MNCF, but not KM+, bound to rat IgE. In rats that were depleted of mast cells, neutrophil recruitment by MNCF and KM+ were significantly reduced indicating that mast cell activation provides an amplification loop for the neutrophil recruitment induced by these lectins. The present study supports the concept that mammalian lectins play a fundamental role in innate immunity.

Animals↗
PubMed2002

Sm60, a mannose-binding protein from Schistosoma mansoni with inflammatory property.

We demonstrate here that a mannose-binding protein from Schistosoma mansoni, termed Sm60, was recovered in the mannose-eluted fraction (Man(+)) upon affinity chromatography on immobilised mannose of the soluble antigen fraction from adult worm tegument and cercariae. Sm60 was detected in the Man(+) fraction as a prominent doublet with an apparent molecular mass of 60-66 kDa by SDS-PAGE and appeared as a single band with a pI of approximately 6.9 by isoelectrofocusing. Sm60 was also detected in preparations of schistosomula extract and soluble egg antigens using a mouse polyclonal anti-Sm60 serum on immunoblotting assay. This antiserum demonstrated that Sm60 was localised on the tegument of S. mansoni adult worm. In order to determine the role of Sm60 in host-parasite interactions, we showed that Sm60 induced in vitro migration of human neutrophil in a dose-dependent manner and in vitro mast cell degranulation. Sm60 triggered these activities through its carbohydrate-binding site, since these activities were selectively inhibited by 0.2 M D-mannose, but not by 0.2 M D-galactose. Furthermore, Sm60 induced in vivo neutrophil migration. In contrast, mast cell-depleted rats presented a significant reduction of the neutrophil migration induced by Sm60 as compared with non-depleted controls. These data suggest that in vivo neutrophil migration induced by Sm60 is modulated by mast cell-dependent mechanisms. Sm60 might play a key role in the host-parasite interaction, and its characterization opens perspective to examine the role of this molecule in the biology of S. mansoni.

Animals↗
PubMed2001

Identification and isolation of rat bone marrow-derived mast cells using the mast cell-specific monoclonal antibody AA4.

Previous studies of mast cell maturation, structure, and function have been hampered by the lack of mast cell-specific markers. In this study, using a well-characterized mast cell-specific monoclonal antibody, MAb AA4, mast cells from rat bone marrow in various stages of maturation were isolated and characterized. The very immature mast cells, which have not been previously described, contained few granules and would not be recognized as mast cells by standard cytological methods. Pure populations of mast cells were isolated from the bone marrow using MAb AA4-conjugated magnetic beads. The same stages of maturation were observed in the isolated mast cells as were seen in the unfractionated bone marrow. All of these cells were immunopositive for the alpha-subunit of Fc epsilon RI, IgE, and c-kit, confirming their identity as mast cells. By direct counting of immunolabled cells and by flow cytometry, approximately 2.4% of the cells in the bone marrow are mast cells. Staining with toluidine blue and berberine sulfate, as well as RT-PCR of the cells, indicates that these cells are connective tissue-type mast cells. The use of immunological methods for identification of mast cell precursors should facilitate the study of these cells. (J Histochem Cytochem 49:219-228, 2001)

Animals↗
PubMed1998

Heparin potentiates in vivo neutrophil migration induced by IL-8.

Chemokine IL-8 attracts neutrophils by a haptotactic gradient, made possible by its interaction with proteoglycans of the extracellular matrix. Heparan sulfate, but not heparin, potentiates the attraction exerted in vitro by IL-8. In the present study we first confirmed this in vitro phenomenon, observing that IL-8 activity was potentiated 100% by heparan sulfate, but not by heparin. Then, we evaluated the interference of heparan sulfate or heparin on in vivo neutrophil migration induced by IL-8. The activity of rat IL-8 (3.5 microg/animal) preincubated with heparan sulfate (50 microg/animal) or heparin (77 microg/animal) was assayed on the rat dorsal air pouch. Contrary to in vitro experiments, heparin, but not heparan sulfate, potentiated the in vivo IL-8 activity two-fold. We investigated the relationship between this observation and that reported by others, that IL-8-induced migration depends on the presence of mast cells, which contain heparin-rich granules. We studied the neutrophil migration induced by IL-8 (3.5 microg/animal) into the rat peritoneal cavity depleted of mast cells. Neutrophil migration was reduced by 32% when compared to that observed in normal animals. The response of depleted rats was reconstituted by preincubation of IL-8 with heparin (77 microg/animal). These data suggest that heparin released from cytoplasmic granules may be the contribution of mast cells to IL-8-induced neutrophil migration.

Animals↗
PubMed1997

Immunocytochemical identification of immature rat peritoneal mast cells using a monoclonal antibody specific for rat mast cells.

The lack of immunological or morphological markers makes identification of immature mast cells difficult. In the present study we have used a rat mast cell specific monoclonal antibody (mAb AA4) to immunolabel mast cells during repopulation of the peritoneal cavity. Peritoneal cells were collected six days after injection of distilled water and examined by light and electron microscopy. mAb AA4 stained immature mast cells in various stages of maturation including a population of very immature mast cells that could not be identified using conventional staining methods. These cells had virtually no cytoplasmic granules and peripherally located lobated nuclei. Thus, immunolabeling with mAb AA4 has revealed a population of very immature mast cells not previously reported during repopulation of the peritoneal cavity.

Animals↗
PubMed1997

Mast cell maturation in young rats: a histofluorescence and cytochemical study.

Since they are not submitted to experimental alterations new-born rats are useful for the investigation of mast cell maturation and were therefore analysed in the present study. In the mesentery of new-born rats immature mast cells were present within and close to fat sheaths containing blood vessels. On day 15, mast cells were also found in mesentery windows and generally in a more advanced stage of maturation. On day 30, the distribution and maturation of mast cells were similar to those found in adult rats. In new-born rats, immature mast cells contained a few metachromatic granules, which showed a positive fluorescence after berberine sulfate staining for heparin and after exposure to paraformaldehyde for serotonin detection. Orthophthaldialdehyde-induced fluorescence for histamine demonstration was negative. On day 15, heparin and serotonin fluorescence were increased and histamine fluorescence became positive. Electron microscopically most mesentery immature mast cells of new-born rats had a well developed Golgi apparatus and rough endoplasmic reticulum, numerous mitochondria and an indented nucleus. The few cytoplasmic granules were large and some of them showed a positive trimetaphosphatase reaction in their periphery. On day 15, most mast cells were almost full of granules. On day 30, mast cells could not be distinguished from those in adult rats. These results show that mast cell maturation in young rats differs from that in adult animals after peritoneal distilled water injection.

Animals↗
PubMed1997

Immunomagnetic isolation of rat bone marrow-derived and peritoneal mast cells.

Mast cells are difficult to purify from heterogeneous cell populations and to preserve, especially for pre-embedding immunostaining at the ultrastructural level. We have developed a technique that permits the isolation of a pure population of mast cells suitable for immunocytochemical studies. A rat mast cell-specific monoclonal antibody (MAb AA4) conjugated to tosylactivated Dynabeads 450 was used to immunomagnetically separate mast cells from rat bone marrow and peritoneal cell suspensions. Approximately 85% of the mast cells were recovered in the positive population that comprised virtually pure mast cells. After microwave fixation, morphological examination showed that the cells were intact and retained their ultrastructural detail. Mast cells in all stages of maturation were immunolabeled with a panel of antibodies after immunomagnetic separation. The combination of immunomagnetic separation followed by immunostaining should prove useful for the study of mast cell maturation and for the characterization of other specific cell types that are present in tissues in only limited numbers.

Animals↗
PubMed1996

Binding of antibody to the gamma subunit of FCepsilonRI in rat basophilic leukemia cells results in morphological changes without inducing histamine release.

The high affinity IgE receptor on mast cells and basophils is composed of 3 subunits, alpha, beta and gamma. A polyclonal antibody was raised in rabbits to a 13 amino acid synthetic peptide corresponding to the amino terminal portion of the gamma subunit. The antiserum was screened using Western blots of solubilized RBL-2H3 cells and 125I goat anti-rabbit IgG. After purification of the serum on a protein G column, RBL-2H3 cells, mouse mast cells, and human basophils showed a doublet at 20 000 kDa. When 125I labeled, saponin-permeabilized cells were immunoprecipitated with the anti-gamma antibody, all 3 subunits of the IgE receptor complex coprecipitated. Furthermore, binding of the antibody to the cell surface did not induce histamine release. By immunofluorescence of fixed cells, the receptor was evenly distributed in the RBL-2H3 cells. Although no capping was observed when the cells were incubated with the antibody prior to fixation, the antibody did stimulate endocytosis when it was bound to the cells at 25 degrees C or at 37 degrees C, but not at 4 degrees C. Binding of the antibody to the RBL-2H3 cells also induced cell spreading and ruffling of the plasma membrane. The results of this study indicate that the gamma subunit of the high affinity IgE receptor may play a role in signal transduction.

Animals↗
PubMed1995

Microwave fixation improves antigenicity of glutaraldehyde-sensitive antigens while preserving ultrastructural detail.

Microwave fixation for electron microscopy has been used primarily for post-embedding immunocytochemistry. The present study examined the ability of microwave fixation to preserve the antigenicity of glutaraldehyde-sensitive antigens for pre-embedding immunocytochemistry. Five monoclonal antibodies (MAbs) directed against cell surface components of rat mast cells were tested. The MAbs failed to show any labeling of conventionally fixed rat bone marrow-derived mast cells even at glutaraldehyde concentrations as low as 0.1%. Strong staining of mast cell plasma membranes was seen when bone marrow was initially fixed with 2% formaldehyde and then refixed in 2% glutaraldehyde/2% formaldehyde after immunostaining. However, the ultrastructural preservation of the cells was poor. Antigenicity and morphological detail were both preserved when bone marrow was fixed in 0.05% glutaraldehyde/2% formaldehyde for 4 sec in a 550-W microwave oven. With this method, mast cells in various stages of maturation as well as cells that did not contain granules were immunoreactive. This method should prove useful with antigens from many different cell types that are sensitive to glutaraldehyde fixation.

Animals↗
PubMed1993

Ultrastructural similarity between bat and human mast cell secretory granules.

Mast cells in the tongue of the bat (Artibeus lituratus) show a well-developed Golgi area and abundant mitochondria in the granule-free perinuclear cytoplasm. Rough endoplasmic reticulum profiles, free ribosomes, mitochondria, bundles of filaments and a great number of secretory granules are found throughout the remaining cytoplasm. The granules, of various shapes and sizes, are simple containing an electron-dense, homogeneous matrix, coarse particles or cylindrical scrolls, or combinations (cylindrical scrolls with either electron-dense, homogeneous matrix or coarse particle contents). Up to now, scroll-containing granules have been considered to be a unique feature of human mast cells.

Animals↗
PubMed1990

Cytochemical demonstration of acid phosphatase, trimetaphosphatase and basic protein in rat peritoneal mast cells during 48/80 induced exocytosis.

Acid phosphatase (AcP-A), trimetaphosphatase (TmP-A) activities and basic protein reaction were cytochemically studied in rat peritoneal mast cells 15 minutes after stimulation by compound 48/80. The AcPase reaction was positive in slightly altered granules, but negative in those more intensely altered, and also in unaltered granules. The TmP-A reaction was negative in altered granules and positive in a few unaltered granules. These results suggest that mast cells have two populations of granules, one, comprising most granules, is AcP-A positive and is exocytosed. The other, smaller, is TmP-A positive, and is not exocytosed. Intact granules gave a strong positive reaction with amoniacal silver nitrate (AS), which detects basic protein. This reaction decreased in intensity with increasing granule alteration.

Acid Anhydride Hydrolases↗