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Biomedical subjects

H Bazin

Publications and source records attributed to H Bazin.

At least 235 records · Page 13Linked to original sources
PubMed1982

Rat hybridoma antibodies against canine parvovirus.

Hybrid cells have been produced by fusion between rat myeloma cells IR983F and spleen cells from a LOU rat immunized with canine enteritis parvovirus. Four stable cell lines were selected each secreting a monoclonal antibody directed against this virus. By indirect immunofluorescence, the antigenic determinants recognized by these antibodies were found to be present not only in canine parvovirus infected cells but also in cells infected by the related parvoviruses of mink enteritis and feline panleukopenia. Two of the monoclonal antibodies inhibit hemagglutination by the canine virus and neutralize its infectivity. Hybrid cells were transplanted into histocompatible animals, and large amounts of the antibodies were obtained.

Animals↗
PubMed1982

Anti-IgE and Con A-induced histamine release from mast cells of four rat strains: correlation with total serum IgE.

Anti-IgE- and Con A-induced histamine release from serosal mast cells were compared to each other and to total serum levels of IgE in non-immunized, alum-injected, and Silica gel-injected rats of the BN, Fischer, PVG, and SD strains. The results indicate that the degree of anti-IgE- and Con A-induced release is strain-dependent and varies with immunization conditions. Furthermore, there is a gross but not complete correlation between the degree of serosal mast cell histamine release induced by the two secretagogues. However, Con A- or anti-IgE-induced release could significantly be correlated to serum levels of total IgE only in the Fischer strain but not in the BN or the PVG strains. In the SD strain, Con A-induced release correlated to serum IgE levels in Silica gel-injected but not in alum-injected animals.

Animals↗
PubMed1982

Conformational studies of rat monoclonal immunoglobulin E.

Two monoclonal IgEs (IR 2 and IR 162) were studied in terms of their conformational features by circular dichroism and differential u.v. absorption. The studies were performed both on the native proteins and under different conditions known to affect the biological properties of IgE (heating at 56 degrees C, acid pH, and presence of reducing agents). Whereas IgE IR 162 appeared to undergo significant conformational changes upon heating and at acid pH, IgE IR 2 was found to be unaffected or less affected by these treatments. The two monoclonal IgEs were found to be equally effective in blocking passive sensitization by IgE antibodies. However, the blocking capacity of IgE IR 162 was affected much more by heating at 56 degrees C than that of IgE IR 2.

Animals↗
PubMed1982

Relation between bronchial reactivity to antigen in vivo and serum IgE and IgG2a antibody levels in rats.

Sprague Dawley rats were immunized with graded doses of ovalbumin (OA) together with alum. The capacity of the animals to produce a bronchial anaphylactic response to intravenous antigen challenge was related to serum OA-IgE and OA-IgG2a antibody levels estimated by radioimmunoassay. A significant correlation between bronchial anaphylactic response capacity and OA-IgE antibody levels was found under a few, but not all, of several carefully chosen experimental conditions. No correlation was demonstrable between the in vivo reactivity of the animals and their serum levels of OA-specific IgG2a antibodies.

Anaphylaxis↗
PubMed1982

Evidence that tissue mast cells derive from mononuclear phagocytes.

A new method has been developed that allows in vitro differentiation of rat mast cells from precursor cells in the absence of feeder layers. In the present investigation, the precursor cells are further characterized as to their nature, state of activation and distribution in different organs of the rat. The data support our previously published evidence, based on morphology and enzyme-cytochemical reaction patterns that the precursor cells are mononuclear phagocytes. Peritoneal macrophages elicited by mineral oil, thioglycollate or proteose-peptone have lost the ability to differentiate into mast cells. Single cell suspensions of spleen and bone marrow contain mast cell precursors, while cells from mesenteric lymph nodes and thymus or purified lymphocytes never yield mast cells in this culture system.

Animals↗
PubMed1982

Peripheral localisation of an IgE immune response at axillary lymph nodes draining the site of a local parasitic infection.

Wistar-Furth rats were infected subcutaneously with L3 larvae of Dipetalonema viteae, filaria of Meriones libycus. Lymph nodes draining the site of immunization contained numerous IgE-staining cells identified as lymphoid cells. In other lymphoid tissues, IgE-staining cells were rare. They were absent in the lamina propria of the small intestine. These data support the view that IgE lymphoid precursors are present in peripheral lymph nodes.

Animals↗
PubMed1982

[Pathogenesis of post-irradiation infection. 2. Role of polynucleated neutrophils in the defense of irradiated rats against Yersinia enterocolitica].

Wistar R inbred rats showed a substantial mortality when they were given Yersinia enterocolitica eight days after a 6.5 Gy total body irradiation. The possibility to abolish the high susceptibility of these irradiated rats to Yersinia enterocolitica by intravenous injections of isogenic neutrophils is presented: irradiated rats injected with 7 to 10.10(7) isogenic neutrophils, by the intravenous route, just before or after the administration of Yersinia enterocolitica, were not susceptible. On the contrary, control irradiated rats, not transfused, were killed by the same bacterial challenge.

Animals↗
PubMed1982

In vitro and in vivo effector function of rat IgG2a monoclonal anti-S. mansoni antibodies.

Rat IgG2a monoclonal antibodies have been produced after fusion of spleen cells from LOU/C rats infected with S. mansoni for 5 wk and IR983F nonsecreting rat myeloma cells. The cell supernatants of one particular IgG2a-producing clone (IPL Sm1) as well as ascitic fluids induced by this clone revealed anti-S. mansoni activity detected by immunofluorescence on schistosoma sections. In vitro studies of the effector function of such antibodies revealed that the rat IgG2a monoclonal antibodies mediated high levels of rat eosinophil-dependent cytotoxic effect against S. mansoni schistosomula, similar to that obtained with 5-week infected rat serum. Passive transfer experiments carried out with IPL Sm1 ascitic fluid showed a significant level of passive protection against a challenge infection. These results indicate a possible use of the monoclonal antibodies in analyzing in vivo functions of IgG2a antibodies, as well as in isolating potentially protective target antigens.

Antibodies, Monoclonal↗
PubMed1981

Origin and fate of IgE-bearing lymphocytes. I. Peyer's patches as differentiation site of cells. Simultaneously bearing IgA and IgE.

Peyer's patches (PP) from adult conventionally raised (C) and germ-free (GF) rats of the same age differed strikingly in the distributions of cells bearing membrane-bound immunoglobulin of the different isotypes. High concentrations of cells with membrane-bound IgE (approximately 20% of total cells determined by indirect immunofluorescence) were found in PP of rats, whereas IgE+ cells were absent from PP of C rats. The numbers of IgA+ cells were almost threefold higher in PP of GF rats when compared with C rats. In contrast, PP of GF rats had greatly reduced numbers of IgM-bearing cells (4%) when compared with C rats (23%); in some experiments virtually no IgM-bearing cells were detected. The levels of IgA- and IgE-bearing cells in spleen of GF rats were increased (to 11% and 7%, respectively). Of the IgE-bearing cells in PP and spleen of GF rats, approximately one-half were simultaneously positive for IgA. When these PP cells were treated with pronase to remove membrane bound immunoglobulins and maintained in culture, both IgE and IgA reappeared within 12 h. The proportion of doubly labeled cells was similar to that of the untreated population. No IgE+ cells were detected in bone marrow of C of GF rats at any time, in agreement with the findings of Ishizaka et al., although up to 20% of bone marrow cells bore other immunoglobulin isotypes, suggesting that IgE-bearing cells arise in the PP either de novo or by switching from precursors carrying IgM or IgA.

Animals↗
PubMed1981

Specificity of fc receptors for IgG2a, IgG1/IgG2b, and IgE on rat macrophages.

To characterize the Fc receptors on rat alveolar and peritoneal macrophages (M phi), we analyzed their ability to form rosettes with fixed ox erythrocytes (Eo') coated with myeloma proteins of all rat Ig classes and with fresh erythrocytes (Eo) sensitized with rat IgG1 and IgG2, rabbit IgG and IgM, and mouse IgA antibodies. The M phi formed rosettes with Eo' coated with rat myeloma proteins of classes IgG1, IgG2a, IgG2b, and IgE but not IgG2c, IgA, IgM, and IgD. Rat M phi also formed rosettes with Eo' coated with human IgG1, IgG3, IgG4, mouse IgG1, IgG2a, IgG2b, and rabbit IgG. Furthermore, rat M phi formed rosettes with Eo sensitized with rat IgG1, IgG2, or rabbit IgG antibodies but not with Eo sensitized with rabbit IgM or mouse IgA antibodies. Trypsin treatment of rat M phi abolished IgG1/IgG2b and IgE but not IgG2a rosettes. The IgG2a and IgE rosettes were Ig class specific because they were inhibited only by rat IgG2a and rat IgE, respectively. In contrast, IgG1 and IgG2b rosettes were inhibited equally by IgG1 and IgG2b. Heterologous IgG inhibited IgG1/IgG2b but not IgG2a rosettes. Rat IgE inhibited rat IgG1, IgG2b, and heterologous IgG rosette formation on rat M phi. Although Eo' coated with rat IgE formed rosettes with mouse P388D1 macrophagelike cells, rat IgE did not inhibit IgG rosettes on these cells. Similarly, Eo' coated with human IgE formed rosettes with human U937 macrophage-like cells, but human IgE did not inhibit IgG rosettes on these cells. The results indicate that rat M phi have at least three distinct Fc receptors: one is specific for rat IgG2a and is trypsin resistant; a second is specific for rat IgE and is trypsin sensitive; and a third reacts with rat IgG1 rat IgG2b, and heterologous IgG and is trypsin sensitive. Rat IgE inhibited IgG1/IgG2b rosettes undirectionally and uniquely on rat M phi.

Animals↗
PubMed1981

Marginal zones: the major B cell compartment of rat spleens.

The marginal zones of rat and human spleens are a broad band of cells, which surround the small lymphocyte area of the white pulp. Staining for acid phosphatase and alpha-naphthyl acetate esterase activity indicates that the majority of cells in this compartment are intermediate-sized lymphocytes. Macrophages only form a minor component. Using quantitative histology, it is shown that the marginal zones are the largest white pulp compartment in terms of volume. They contain approximately as many lymphocytes as the small lymphocyte zones. The cells of the marginal zone are strongly C3- and Fc receptor-positive. While the cells of this zone have demonstratable surface membrane Ig, it is difficult to exclude that this is not passively absorbed. Other means were therefore sought to determine the lineage of lymphocytes in this area. First, the cells in this zone do not bear appreciable quantities of the rat T cell selective antigen detected by the monoclonal antibody W313. Second, marginal zone cells are present in normal numbers in congenitally athymic "nude" rats. Finally, marginal zones do not become populated with lymphocytes in rats treated from birth with anti-mu antibody. Further experiments showed that marginal zone lymphocytes do not recirculate.

Animals↗
PubMed1981

Tryptic cleavage of rat IgG: a comparative study between subclasses.

Monoclonal rat IgG belonging to the 4 rat IgG subclasses, and some IgG subclasses isolated from normal rat serum were subjected to enzymatic degradation with trypsin. Differences in the products of tryptic digestion were observed according to the IgG subclass. IgG2b and IgG2c were degraded mainly into Fab and Fc fragments. IgG1 and IgG2a appeared resistant to such cleavage. However, tryptic digestion of the latter two produced two fragments separated only in dissociating media. Results of the studies suggest that one of the fragments (mol. wt. 13,000) probably consists of most of the variable domain of the gamma heavy chain, while the second (mol. wt. 120,000) consists of the IgG deleted of the VH regions.

Animals↗
PubMed1981

Expression of IgD may use both DNA rearrangement and RNA splicing mechanisms.

From a library of mouse sperm DNA, we have isolated two overlapping clones which contain the C(delta) gene. One of these clones also contains the C(mu) gene. The C(delta) gene is separated from the C(mu) membrane exons by approximately 2 kilobases (kb) of DAN. The C(delta) gene was identified by (a) hybridization to poly(A)(+)RNA prepared from the IgD-producing rat plasma cell tumor IR731, and (b) homology of a translated nucleotide sequence to the amino acid sequence of the human delta chain. The C(delta) gene spans 8 kb of DNA in the germ line. Plasmid subclones of the C(delta) gene were used as probes in Southern and RNA blot experiments. RNA blot analysis of cytoplasmic poly(A)(+)RNA from IR731 and a mu(+)delta(+) B-cell hybridoma revealed 1.6- and 2.7-kb delta mRNA species with different 3' ends, which presumably encode the secreted and membrane-bound forms, respectively, of the delta chain. Southern blot analysis of DNA from two mu(+)delta(+) lymphomas revealed that the C(delta) gene is in the germ-line configuration in each case. Restriction map analysis of C(mu) and C(delta) genomic clones isolated from a library of normal mu(+)delta(+) B-cell DNA also gave no evidence for DNA rearrangement in the region between the C(mu) and C(delta) genes. Taken together, these data suggest that IgD expression in mu(+)delta(+) B cells does not involve a V(H)-to-C(delta) DNA switch rearrangement. We propose that simultaneous expression of C(delta) and C(delta) with a single V(H) gene is mediated by two alternative routes of RNA processing of a primary nuclear transcript which contains the V(H), C(mu), and C(delta) genes. In contrast, analogous experiments with myeloma IR731 DNA revealed that the C(mu) gene has been deleted from the myeloma DNA and that the C(delta) gene has undergone DNA rearrangement, presumably including a switch recombination of the V(H) gene from the C(mu) to the C(delta) gene. These results indicate that two alternative mechanisms may be used in the expression of IgD molecules-RNA splicing in B cells and DNA rearrangement in plasma cells.

Animals↗
PubMed1981

Pathogenesis of post-irradiation infections. I. Yersinia enterocolitica administered to normal and irradiated rats.

Infections after irradiation can be due to a great variety of microorganisms many of which are normally non-pathogenic or conditionally pathogenic for the host. The strain of Y. enterocolitica used was not pathogenic to a variety of unirradiated rats nor to athymic or B lymphocyte deprived, macrophage depleted rats, nor to normal rats irradiated by 5.7 Gy 24 hours before. However similarly irradiated rats receiving Y. enterocolitica 5 to 10 days later showed a substantial mortality. It is concluded that the radiosensitive mechanism for protection against Y. enterocolitica is not humoral nor cellular immunity as mediated by T and B lymphocytes or macrophages.

Animals↗