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Biomedical subjects

H Bazin

Publications and source records attributed to H Bazin.

At least 199 records · Page 11Linked to original sources
PubMed1984

Rat monoclonal antibodies. II. A rapid and efficient method of purification from ascitic fluid or serum.

A technique for purifying rat monoclonal antibodies from ascitic fluid or serum is described which is based on 2 facts. First, approximately 95% of rat immunoglobulin light chains are of the kappa type. Second, an allotypy in the rat species is located on the constant part of the kappa light chain. By use of a mouse monoclonal antibody with specific binding affinity for the Ig kappa-1a allotype on the kappa light chains of the LOU inbred rat strain, it is possible with immunoaffinity chromatography to isolate LOU Ig kappa-1a-bearing immunoglobulins from the serum proteins, including the immunoglobulins, of rats of Ig kappa-1b allotype. LOU histocompatible hybridomas synthesizing the Ig kappa-1a allotype can be transplanted into rats congenic with the LOU inbred strain carrying the Ig kappa-1b allotype, since LOU rats with the Ig kappa-1a kappa light chain allotype and congenic LOU Ig kappa-1b rats with the Ig kappa-1b kappa light chain allotype are fully histocompatible. The serum or ascitic fluid of the recipients is applied to an immunoabsorbent column to which mouse monoclonal antibody against the Ig kappa-1a allotype is coupled. The serum proteins, including the host immunoglobulins pass through the column. An appropriate buffer is used to elute the monoclonal antibodies in a second step. The same technique may be employed for other monoclonal antibodies. A reciprocal system using mouse monoclonal antibodies against Ig kappa-1b rat allotype can be used, a plasmacytoma or hybridoma synthesizing Ig kappa-1b kappa light chain being transplanted into an Ig kappa-1a kappa light chain synthesizing rat. The method is rapid, efficient and inexpensive. Its limitation is with respect to lambda-type monoclonal antibodies, which are relatively rare.

Animals↗
PubMed1984

Rat monoclonal antibodies. I. Rapid purification from in vitro culture supernatants.

A technique for purifying rat monoclonal antibodies quickly and efficiently from in vitro culture supernatants is described. It is based on the fact that more than 95% of rat immunoglobulins carry kappa light chains. A mouse monoclonal antibody with suitable binding affinity for rat kappa light chains is immobilized on solid support and used to purify rat immunoglobulins. Milligrams of rat monoclonal antibodies may be rapidly concentrated from culture supernatants with high recovery. Rat monoclonal antibodies expressing lambda light chains (about 5% of the total) may be purified in a similar way with an appropriate anti-rat lambda chain monoclonal antibody.

Animals↗
PubMed1984

Marginal zone B cells express CR1 and CR2 receptors.

Opsonized yeast is known to bind strongly to the marginal zones in frozen sections of rat spleen (Kumararatne, D. S. et al., Eur. J. Immunol. 1981. 11: 858). This study reports an analysis of the cells involved in this binding. Sheep red cells coated respectively with C3b, C3bi or C3d were used as indicator cells. These showed homogeneous binding of both C3b and C3bi to marginal zones and germinal centers. C3d-coated red cells bound in a uniform speckled pattern to marginal zones. They also bound to germinal centers and the small lymphocyte zones of the follicles. Selective depletion experiments were undertaken to show that binding to marginal zones was a property of the IgM+ and IgD- B cells characteristic of this area. Binding to germinal centers was attributable to follicular dendritic cells. The C3d receptors in follicles were shown to be on IgM+ and IgD+ small B lymphocytes.

Animals↗
PubMed1984

Polyclonal IgE increase after HgCl2 injections in BN and LEW rats: a genetic analysis.

An autoimmune disease and a dramatic increase in total serum IgE concentration are observed in BN rats that are chronically injected with HgCl2. In contrast, LEW rats do not develop the characteristic glomerulonephritis and are very "low IgE responders". In this study, we examined the genetic control of total serum IgE increase after HgCl2 injection in F1 and F2 hybrids, in both backcrosses between LEW and BN rats, and in LEW.1N congenic rats. Genetic analysis was performed using peak IgE concentrations expressed as log microgram/ml. A high IgE phenotype was found to be dominant. Eighty-five percent of F2 variance was due to genetic factors (VG) while only 15% of this variance was caused by environmental factors (VE). From observations in F2 hybrids and backcrosses, estimations of additive variance (VA) and dominance variance (VD) were made following three different methods. Genetic control by about four loci is demonstrated. One of these genes is RT1-linked. This gene contributes to 25% of the phenotypic difference observed between BN and LEW rats. No correlation was found between the peak total IgE level and autoimmune disease based on IgG deposition in spleen and/or kidney.

Animals↗
PubMed1984

Anti-IgE-induced histamine release from rat tissues passively sensitized in vivo with myeloma IgE differs with strain and mast cell source.

Four different strains of rats, BDII, E3, LE, and OM/N, each with a low basal serum level of IgE, were examined with respect to anti-IgE- and ConA-induced release of histamine from serosal mast cells and chopped lung tissue. Tests were performed before and three days after i.p. injection of a graded dose of myeloma IgE (IR 162)-containing ascitic fluid. There was a clearcut strain difference in response capacity with respect to ConA- and anti-IgE-induced release of histamine from serosal mast cells before myeloma IgE-injection. Response capacity increased in some but not all strains after myeloma IgE injection; increase in response capacity of serosal mast cells did not correlate to that of chopped lung tissue. Analogous findings were observed when two of the strains, LE and E3, were passively sensitized by i.p. injection with serum containing another myeloma IgE (IR2). These results indicate that differences exist between mast cells of different rat strains, and within strain between mast cells of various tissues in capacity to become sensitized to myeloma IgE.

Animals↗
PubMed1984

Suppressive effects of anti-mu serum on the development of collagen arthritis in rats.

Sprague-Dawley rats were maintained in environmentally isolated conditions and some of them were injected beginning at birth with rabbit anti-mu serum to suppress B-cell maturation. All rats were subsequently immunized with chick type II collagen. Ten (28%) of 36 rats injected with anti-mu antiserum failed to develop serum hemagglutinating antibodies to collagen, and there was a significant (P less than 0.0003) reduction in the IgG-specific antibody titer to collagen in these 10 rats compared to the other 26 rats in this group. Only 1 (10%) of the antibody-suppressed rats developed arthritis compared to 20 (77%) of the 26 other rats in the anti-mu-treated group (P less than 0.001). Twenty-two (61%) of 36 immunized rats administered rabbit anti-ovalbumin serum and 14 (88%) of 16 immunized rats kept in the axenic conditions developed arthritis. Delayed-type hypersensitivity to collagen did not differ significantly between the groups. These data provide indirect evidence that antibodies play a role in the inception of collagen arthritis.

Animals↗
PubMed1984

Production of monoclonal anti-glomerular basement membrane antibodies during autoimmune glomerulonephritis.

Monoclonal anti-glomerular basement membrane (GBM) antibodies were obtained by fusing spleen cells from Brown-Norway (BN) rats injected with mercuric chloride with IR 983 F, a nonsecreting rat myeloma cell line. These antibodies showed the same pattern of fixation on renal basement membranes by indirect immunofluorescence. One of them was developed. It reacted both in vivo and in vitro with GBM but failed to react with collagenase-digested GBM, laminin, and collagen IV. This monoclonal antibody which resembles the kidney acid eluate obtained from BN rats injected with mercuric chloride induced a weak and transient proteinuria when intravenously injected into normal BN rats.

Animals↗
PubMed1984

Differential reduction of the inter-chain disulfide bonds of rat immunoglobulin E: relation to biological activity.

Monoclonal rat IgE was reduced over a range of dithiothreitol (DTT) concns. The number of disulfide bonds reduced and their location in the IgE molecule were studied. One millimolar DTT was found to split the two inter-heavy-chain disulfide bonds of the C epsilon 2 domain while increasing DTT concn to 10 mM split the two inter-heavy-light-chain disulfide bridges. Therefore, the sensitivities to reduction of disulfide bonds in rat IgE were found to be the opposite of those in human IgE. In addition, the results indicated the absence, in rat IgE, of the intra-epsilon-chain labile disulfide bond of the C epsilon 1 domain, which is reduced by 2 mM DTT in human IgE. Circular dichroism studies showed significant modifications, mainly of tertiary structure, for rat IgE reduced with 10 mM DTT, but not for IgE reduced with 1 mM DTT. The ability to block passive sensitization with reaginic antibody was not modified when IgE was reduced with 1 mM DTT (which split the two inter-heavy-chain disulfide bonds), but was lost when inter-heavy-light-chain bridges were reduced with 10 mM DTT. In addition, a non-covalent epsilon-chain dimer was found to have the same blocking activity as native IgE (or IgE reduced with 1 mM DTT). Therefore, the results suggest that reduction of most or all the inter-chain disulfide bonds, in rat as in human IgE, induces changes in quaternary structure, more especially in the relationship between the Fab and Fc parts of the molecule, leading to steric blockade, by Fab, of the binding sites for mast cells present on Fc.

Amino Acid Sequence↗
PubMed1984

Regulation of Fc mu receptor-mediated functions of resident and provoked peritoneal macrophages.

Modifying and/or regulating effects on Fc mu receptor (R) mediated phagocytic and ADCC activity of both resident (r) and provoked (p) peritoneal macrophages (PM) was studied applying drugs affecting the cytoskeleton and cation transport. In addition, the effects of exogenous PGE2 and cyclic nucleotides were also examined. Fc mu-receptors appear to be functionally less significant in provoked PMs than in resident ones since both Fc mu-receptor mediated phagocytosis and ADCC were lower in the formers. The cytoskeletal system is important in the regulation of both Fc mu-receptor-mediated functions. Phagocytosis through Fc mu-receptor is decreased by Cytochalasin B and by Vinblastine treatment, whereas ADCC is enhanced by Cytochalasin B. Extracellular PGE2 and cAMP induced a higher phagocytic activity and suppressed ADCC, whereas cGMP displayed an opposite effect. The sensitivity of Fc mu R-mediated activities to ionophoric and to cytoskeleton-damaging drugs was lower in provoked than in resident PMs. In addition, the regulatory role of PGE2 and of cyclic nucleotides on the same activities was less marked on provoked PMs. In contrast, ouabain inhibits Fc mu R-dependent antigen incorporation and ADCC on provoked PM monolayers only. These findings suggest differing regulatory mechanisms for Fc mu R-mediated functions in provoked PMs as compared with resident ones.

Animals↗
PubMed1984

Immunohistological observations on the spleen B lymphocyte populations from whole-body irradiated rats.

The effects of a single exposure to caesium gamma rays administered to rats at high dose rate have been observed on their spleen B lymphocyte populations. These effects increase with the dose as well as with the time, at least within the following ranges of experimental conditions: from 0 to 12 Gy and observation times of 1 and 3 days after irradiation. Doses less than or equal to 1.50 Gy lead to only a slight reduction of the B lymphocyte populations. On the contrary, doses equal to or greater than 3.50 Gy are extremely destructive for the spleen B lymphocytes. The non-circulating B lymphocyte population of the marginal zone compartment seems more susceptible to ionizing radiations than the circulating B lymphocyte population of the follicular compartment.

Animals↗
PubMed1984

Macrophage triggering by aggregated immunoglobulins. II. Comparison of IgE and IgG aggregates or immune complexes.

Macrophages incubated with complexed or aggregated IgE released beta-glucuronidase (beta-G) within 30 min. In contrast in the presence of aggregated or complexed IgG, macrophages liberated equivalent amount of beta-G only after 6 h incubation. In addition the rapid macrophage stimulation induced by aggregated IgE was also followed by a faster 3H-glucosamine incorporation when compared to the delayed activation caused by aggregated IgG. However, macrophages stimulated either by IgG or by IgE oligomers produced the same percentage of plasminogen activator at 24 h. In contrast, while the interaction between macrophages and aggregated IgE was only followed by a peak of cyclic GMP and a beta-G release during the first 30 min of incubation, the interaction between macrophages and IgG oligomers was accompanied by a simultaneous increase of cyclic GMP and AMP nucleotides and by an absence of beta-G exocytosis. Moreover, the beta-G release induced by aggregated IgE was increased when macrophages were preincubated with aggregated IgG. This additive effect was not observed in the reverse situation. Finally macrophages activated by IgG oligomers were demonstrated to exert a cytotoxic effect on tumour cells and to kill schistosomula in the presence of a low level of complement. Taken together these results underline the peculiar ability of aggregated or complexed IgE to trigger rapidly the macrophage activation compared to aggregated IgG and can explain the important role of complexed IgE in some macrophage dependent cytotoxicity mechanisms (i.e. in parasitic diseases).

Animals↗
PubMed1984

In vivo kinetics and nature of rat IgE-bearing lymphocytes after IgE stimulation.

Surface IgE-bearing (sIgE+) cells were studied in BN and rnu/rnu athymic rats after Nippostrongylus brasiliensis infection or i.p. injection of unpurified or purified IgE from plasmacytoma ascitic fluid. The number of sIgE+ cells increased markedly after a serum IgE increase without change in the proportion of sIgM+ and sIgD+ cells. A high percentage of the sIgE+ cells bore cytophilic IgE. Receptors for IgE were induced with a 2.56-micrograms IgE injection/100 g body weight and reached a maximum with 1.6 mg IgE/100 g body weight. They appeared less than 4 hr after a single injection of purified IgE. The number of IgE receptor-bearing cells reached a maximum plateau at 24 hr to day 3 after injection and declined thereafter, to reach the control level on day 9 or 11 after injection. Nearly all the sIgE+ cells of BN rats also bore sIgD, but the number of triple sIgE-sIgM-sIgD+ cells varied in a wide range. Maximum 4.5% of the sIgE+ cells of euthymic rats were T cells. More than 98% of the sIgE+ cells of nude rats were triple sIgM-sIgD-sIgE+ cells, and the majority were cytophilic IgE+. For the most part, the sIgM-sIgD-sIgE+ cells are probably not cells that can differentiate, as generally accepted, in IgE-producing cells. New interpretations of the role of these triple sIgM-sIgD-sIgE+ cells in IgE immune responses are necessary.

Animals↗
PubMed1984

[Ontogenesis and differentiation of IgE B lymphocytes in the rat].

In fetal liver, the stem cells of the B lineage transform into pre-B cells with intracytoplasmic mu-chains and thereafter into mature B cells with IgMc and IgMm. The other immunoglobulin classes appear later. The IgEm B cells appear on the day of birth. They bear IgMm and IgDm. Anti-IgM or anti-IgD suppression, performed from birth, prevents IgE synthesis. IgM and IgD seem to be necessary to IgE lymphocyte differentiation. Neonatal anti-IgE suppression seems to have no influence on IgE lymphocytes, but this result has to be confirmed. IgE immune responses are T-dependent. Neonatally thymectomized animals or rnu/rnu rats are unable to produce IgE immune responses. Axenic rats possess a great number of IgEm-IgAm-bearing cells in Peyer's patches; this is not observed in conventional animals. Nevertheless, the major problems are due to cells with receptors for IgE which must be differentiated from cells with intrinsic IgE. Work is under way to solve these problems.

Aging↗
PubMed1983

Optimal conditions for the preparation of Fab and F(ab')2 fragments from monoclonal IgG of different rat IgG subclasses.

The optimal conditions for the preparation of Fab and F(ab')2 fragments from monoclonal rat IgG of different subclasses are described. Digestion of IgG for 2-4 h at 37 degrees C with 1% (w/w) papaïn at pH 7.0 in the presence of 0.01 M cysteine leads to almost complete cleavage into Fab and Fc fragments. Fab fragments are isolated by sequential chromatography on Ultrogel AcA 44 and on DEAE-cellulose columns. In the case of IgG2c subclass, Fab fragment may be directly isolated by chromatography on Protein A-Sepharose. Production of F(ab')2 fragments from rat IgG1 and IgG2a is obtained with best yield by treatment at acid pH (pH 2.8) before incubation with 1% (w/w) pepsin at pH 4.5 for 4 h at 37 degrees C. For monoclonal IgG2b the best procedure is incubation with S. aureus V8 protease at pH 7.8 (4 h at 37 degrees C with an E/S ratio of 1/30 (w/w]. The best yield of F(ab')2 from monoclonal IgG2c is obtained by incubation for 4 h at 37 degrees C with 1% (w/w) pepsin. F(ab')2 fragments (or the F(ab)2-like fragment released by digestion of IgG2b with S. aureus V8 protease) are isolated by gel filtration on Ultrogel AcA 44.

Animals↗
PubMed1983

Proteolysis of rat IgG subclasses by Staphylococcus aureus V8 proteinase.

Monoclonal IgG belonging to the four rat IgG subclasses (IgG1, IgG2a, IgG2b, IgG2c) and some IgG subclasses from normal rat serum were subjected to enzymatic degradation with Staphylococcus aureus V8 proteinase. The results show that only one subclass, IgG2b, is significantly cleaved by the enzyme, with the release of two main products identified as F(ab)2 and Fc-like fragments. This unique susceptibility of the IgG2b subclass represents therefore an easy means of identification and also offers a simple procedure for a preparation of F(ab)2 fragments from monoclonal IgG2b antibodies.

Animals↗
PubMed1983

Rat AL2, AL3, AL4 and AL5 monoclonal antibodies bind to the common acute lymphoblastic leukaemia antigen (CALLA gp 100).

Four distinct rat monoclonal antibodies against the common ALL antigen (CALLA, gp 100) were obtained in a single fusion. Rat AL2, AL3, AL4, AL5 and the previously reported mouse J5 monoclonal antibodies identified the same subsets of leukaemic cells. AL2 and AL3 reacted weakly with terminal transferase-positive cells in normal bone marrow and foetal liver, as well as with a minority of mature granulocytes in blood. Immunoprecipitation experiments and competitive binding assays demonstrated that the four rat antibodies and J5 bound to the same glycoprotein of approximately 100,000 mol. wt. This set of rat monoclonal antibodies directed against CALLA has not only a diagnostic usefulness but may also be of therapeutic value.

Animals↗
PubMed1983

Parasitological and immunological aspects of Trypanosoma cruzi infection in nude rats.

The role of the thymus on immunity of rats against Trypanosoma cruzi infection was investigated in vivo. The athymic (nu/nu) rats were shown to be significantly more susceptible to the acute phase of the infection than the control nu/+ rats, as measured by increased parasitemia and mortality. Specific anti-T. cruzi antibodies, complement, IgM and IgG2a serum levels were determined. The results would indicate the essential role of antibodies in immunity to acute Chagas' disease through T-dependent immune response.

Animals↗