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Biomedical subjects

H Bazin

Publications and source records attributed to H Bazin.

At least 253 records · Page 14Linked to original sources
PubMed1981

Trypanosoma cruzi infection in B-cell-deficient rats.

The effect of neonatally initiated injections of anti-mu rabbit antiserum on immunity of rats against Trypanosoma cruzi infection was investigated in vivo. Anti-mu treatment resulted in a loss of immunoglobulin M (IgM) and IgG2a synthesis and, subsequently, of antibody production. These rats so treated were shown to be significantly more susceptible to the acute phase of the infection than the control rats treated with normal rabbit serum, as measured by increased parasitemia and mortality. These results indicate the essential role of antibodies, probably in association with complement or effector cells or both, in immunity to acute Chagas' disease.

Animals↗
PubMed1981

Nature of the thymus dependency of mucosal mast cells. III. Mucosal mast cells in nude mice and nude rats, in B rats and in a child with the Di George syndrome.

Mucosal mast cells have been examined in the small intestinal mucosae of nude mice and nude rats, B rats and a child with the DiGeorge syndrome. In all three species, mast cells were present in normal numbers despite the athymic status of the nude mice and nude rats, the vestigial nature of the thymus in the child, and the functionally T lymphocyte-deprived status of the B rats. Connective tissue mast cells were also plentiful in skins and tongues of the nude mice and the child with thymic aplasia. It is concluded that normally neither population of mast cells has a obligatory dependence on the thymus or T lymphocytes for its differentiation, but that mucosal mast cells, under certain conditions of rapid hyperplasia, require an inductive influence provided by T lymphocytes.

Animals↗
PubMed1981

Role of the cytoskeleton in the Fc receptor activity of rat peritoneal macrophages.

High concentration of cytochalasin B (CB) and vinblastine (Vb) inhibited the erythrocyte-antibody (EA) rosette formation of rat peritoneal macrophages (PM). Low concentration of Vb enhanced rosette formation. CB and Vb had the same effect on the rosette formation when anti-SRBC immunoglobulin (Ig) had been previously bound in vivo or in vitro to the Fc receptors (FcR) of the macrophages, suggesting that the intact function of the cytoskeleton is required for the last step of rosette formation. CB and Vb exert a reversible effect on FcR activity. Regeneration of FcR activity was observed also in the presence of 10 microgram/ml cycloheximide. The effect of CB and Vb on rosette formation depends both on the (sub)classes of antibody involved and on the nature of the particulate antigen. Rosettes with living trypanosomes displayed an extremely high CB sensitivity.

Animals↗
PubMed1981

Induction of IgE synthesis and potentiation of anti-ovalbumin IgE antibody response by HgCl2 in the rat.

The present study demonstrates that mercuric chloride (HgCl2) induces a striking increase of total serum IgE in Brown Norway (BN) rats. Values up to several milligrams of IgE per milliliter of serum were observed. No antibody specificity was demonstrated for these IgE. Mercuric chloride also potentiated a specific anti-ovalbumin IgE response when the rats were immunized with ovalbumin. The kinetics of the response to HgCl2 was different from that to an antigenic stimulus alone: total IgE increased together with the potentiated anti-ovalbumin IgE antibody response to reach maximum values about 14 days after initiation of HgCl2 injections. The potentiated IgE antibodies represented only an insignificant fraction of total IgE. All these findings were observed in BN but not in Lewis rats. These data show analogies with those reported after parasitic infection in the rat and suggest similar mechanisms of action.

Animals↗
PubMed1981

Evidence for IgE-dependent cytotoxicity by rat eosinophils.

Human and rodent eosinophils have been shown previously to act as effector cells against Schistosoma mansoni schistosomula by ADCC mechanisms involving IgG antibodies. The present work brings novel evidence for the existence in rat schistosomiasis of an IgE-eosinophil dependent cytotoxicity mechanism. The role of IgE antibodies present in the rat serum after 6 weeks of infection was clearly established by immunoadsorption and inhibition experiments, whereas the participation of IgG and complement in this system could be ruled out. Mast cell products, including ECF-A tetrapeptides, appear to play an essential role in significantly increasing eosinophil cytotoxicity. A kinetic study of the IgG-dependent cytotoxicity mechanism previously described and of this IgE-mediated mechanism according to rat schistosomiasis revealed the preeminent role played by IgG antibodies in early infection, whereas IgE predominated after 6 wk of infection. The possible significance of IgE-eosinophil cooperation in ADCC mechanisms in parasite and nonparasite models is discussed.

Animals↗
PubMed1981

Classes and subclasses of rat antibodies: reaction with the antigen and interaction of the complex with the complement system.

Antibodies against the dinitroaminophenyl (DNAP) haptenic group were raised in outbred CFY rats using HSA or LPS as carrier. Antibodies isolated by immunoadsorbent techniques were resolved into fractions representing distinct isotypes, and the resulting fractions were tested for avidity. Subclass IgG2a was found to contain antibodies of an avidity index lower than those of other IgG subclasses or IgM. IgG2a was the only isotype detected when DNAP-LPS was used for immunization. Complexes containing defined isotypes were compared for their capacity to activate homologous complement. IgGl type antibody-containing complexes displayed a low complement activating capacity compared with those containing IgG2b, IgG2c or IgG2a. The latter subclass when complexed with antigen can thus induce complement-dependent processes in spite of a low avidity. Insoluble complexes of IgG antibodies were rapidly solubilized in rat serum (CRA phenomenon), except those containing predominantly IgG2c.

Animals↗
PubMed1981

Passive cutaneous anaphylaxis inhibition: evidence for heterogeneity in IgE mast cell interaction.

Recent evidence suggests that IgE molecules are heterogeneous with respect to ability to compete with IgE myeloma for sensitization of histamine release from chopped human lung and ability to passively sensitize human basophils for antigen-induced histamine release. These observations prompted further investigation of the possibility that there exists a functional heterogeneity in the IgE molecules with respect to mast-cell binding properties. Using eight different purified rat IgE myeloma proteins, we found that they differ in their ability to inhibit the passive cutaneous anaphylaxis (PCA) reaction of mouse reaginic antisera. This suggests that IgE molecules differ in their ability to bind to mast cell receptors. Since maximal inhibition of different mouse reaginic antisera and mouse IgE hybridomas is achieved with different IgE myelomas, there may exist a functional heterogeneity in mast-cell binding receptors as well.

Animals↗
PubMed1980

Subclass restriction of murine antibodies. III. Antigens that stimulate IgG3 in mice stimulate IgG2c in rats.

The IgG subclass distribution of rat antibodies to 13 different antigens was measured. Antibodies to protein and hapten-protein conjugates were predominantly IgG2a. Antigens labeled thymus-independent type 1, based upon responses in mice, stimulated both IgG2b and IgG2c antibodies, but little IgG2a. Polysaccharide and hapten-polysaccharide antigens (thymus-independent type 2) as well as phosphocholine-keyhole limpet hemocyanin, stimulated predominantly IgG2c antibodies. A division of antigens into essentially the same categories has been made on the basis of subclass restriction in mice. Antigens that stimulate IgG2c in rats stimulate IgG3 in mice. Thus, by comparing subclass preference with a variety of antigens, functional analogues among subclasses in different species can be identified.

Animals↗
PubMed1980

Studies on the incidence of rat ileocecal malignant immunocytoma: vertical transmission of the high tumour incidence.

Monoclonal immunoglobulin-secreting tumours (immunocytomas, myelomas or plasmocytomas) appear with a high or low incidence in 2 sublines, LOU/C and LOU/M respectively, of the same inbred strain of rats. Studies of the reciprocal hybrids of the first generation between both substrains have shown that the transmission of the high tumour incidence from parents to offsprings is determined by the male as well as by the female. Absence of C-type viral particles in LOU/C rats and immunocytomas derived from them suggests that this vertical transmission might be genetically mediated.

Animals↗
PubMed1980

Influence of adrenergic drugs on IgE production.

The influence of some adrenergic drugs (fenoterol, salbutamol, terbutaline as stimulant; propranolol as blocker) on IgE production in the rat was investigated. The drugs were administered orally, mixed in the food. The stimulant drugs caused a significant decrease of total serum IgE but had no influence on the specific IgE antibody response. The beta adrenergic blocker caused a significant increase of total serum IgE but also had no influence on specific IgE. The effect of terbutaline was blocked by propranolol. No influence of these adrenergic drugs on IgA and IgM levels was observed.

Adrenergic beta-Agonists↗
PubMed1980

Effect of neonatal injection of anti-mu antibodies on immunity to schistosomes (S. mansoni) in the rat.

The effect of neonatally initiated injections of anti-mu serum on immunity to reinfection with Schistosoma mansoni in the rat was investigated in vitro and in vivo. Anti-mu treatment resulting in a profound depression of immunoglobulin synthesis dramatically decreased immunity to reinfection assessed by worm recovery technique. Complement-dependent antibody, IgG2a antibody-eosinophil-mediated and IgE-macrophage cytotoxicity reactions were in parallel markedly reduced. These results show the prominent role played by antibody-dependent mechanisms in immunity to schistosomes in the rat.

Animals↗