Circaseptan-circadian rhythmic changes in corneal mitoses of Louvain rats.
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Activity Cycles↗
Biomedical subjects
H Bazin
Publications and source records attributed to H Bazin.
Human IgG and Streptococcus mutans SR protein contain cross-reactive epitopes.
Antigen B, a glycoprotein present on the cell surface of "mutans streptococci," mediates bacterial adherence to teeth surfaces and has been implicated in cross-reactivity with human heart components. Elevated levels of anti-IgG antibodies were generally found in sera of rabbits immunized with protein SR, a B-related protein from Streptococcus mutans serogroup f, or recombinant protein SR (rSR). These anti-IgG antibodies could be involved in the previously mentioned heart cross-reactivities. Results from immunoblots and ELISA analyses demonstrate that these anti-IgG antibodies recognize common epitopes on SR, rSR, and human IgG2 and IgG4 probably located on the Fab region. Furthermore, control experiments with biotinylated human IgG show that the cross-reactions between IgG and SR were not mediated by an FcR mechanism. Direct competition between rSR and human IgG in binding to anti-IgG or anti-SR antibodies confirm that S. mutans SR protein possesses Ag mimicry with human IgG. Our studies provide some evidence that S. mutans SR protein and human IgG H chains share autoimmune epitopes which could play a role in the induction of anti-IgG antibodies and therefore could explain the enhancement of anti-IgG antibody levels observed in rabbits immunized with either S. mutans whole cells or purified B-related Ag.
Animals↗
Synthesis and use of labelled nucleoside phosphoramidite building blocks bearing a reporter group: biotinyl, dinitrophenyl, pyrenyl and dansyl.
The synthesis of protected nucleoside phosphoramidites bearing various markers such as biotinyl, dinitrophenyl, dansyl and pyrenyl groups are reported. These labelled deoxynucleosides phosphoramidites were used for solid phase oligonucleotide synthesis in the same way than the usual protected phosphoramidities without any change in the synthetic cycle and the deprotection step. The new labelled building blocks described herein have been used in conjunction with the labile base protected phosphoramidites ('PAC phosphoramidites') which allowed mild ammonia deprotection, especially recommended for the dinitrophenyl-labelled oligonucleotides. Multiple labelling (i.e. 10 to 20 biotins) can be efficiently and easily performed, on the same oligonucleotide which results in an increase of sensitivity. The polylabelled oligonucleotides are chemically well defined and gave increased signal and low background coloration for in situ hybridisation. The modified oligonucleotides can still be kinased in the normal way as the reporter groups are on the heterocycles.
Biotin↗
Origin and fate of IgE-bearing lymphocytes. II. Modulation of IgE isotype expression on Peyer's patch cells by feeding with certain bacteria and bacterial cell wall components or by thymectomy.
Mechanisms regulating the appearance of sIgE+ B lymphocytes appear to be lacking in adult germfree (GF) rats in that their Peyer's patches (PP) contain high numbers of cells with sIgE (approximately 15% of total cells), one-half of which simultaneously express sIgA, whereas sIgE+ cells are absent from PP of conventional rats (less than 1%). GF rat PP also contain elevated numbers of sIgA+ cells and decreased numbers of sIgM+ cells, with elevated numbers of sThy-1+ RT 7.1+ Ig- T cells, and reduced numbers of sThy-1- RT 7.1+ Ig- T cells. The cellular composition of PP of GF rats was converted to that resembling a conventional rat within 18 h after either 1) use of standard (unautoclaved) food; 2) feeding with certain bacteria (Clostridium difficile, Corynebacterium pseudodiphtheriticum, Mycobacterium tuberculosis, and Klebsiella pneumoniae), in either live or heat-killed, but not autoclaved form; or with certain bacterial cell wall components: murein (peptidoglycan), and its synthetic derivatives, muramyltripeptide phosphatidylethanolamine and desmethyl-muramyldipeptide, but not with LPS, core lipid A or lipoprotein; there was no effect if any bacterial cell wall component was injected i.v.; or 3) thymectomy. Each procedure resulted in elimination of sIgE+ B cells and normalization of the other surface isotypes, and loss of sThy-1+ RT 7.1+ Ig- T cells and normalization of sThy-1- RT 7.1+ Ig- T cells. Irrespective of treatment, no sIgE+ cells were detected in bone marrow, thymus, other lymphoid organs or blood, excluding the possibility that the elimination of these cells from PP was associated with their redistribution to other sites. Thus, exposure to gut flora and bacterial peptidoglycan components may have resulted in IgE isotype switching, either directly or through the mediation of accessory and/or sThy-1+ RT 7.1+ regulatory T cells. The sites in which sIgE+ B cells are down-regulated appear to be PP.
Animals↗
Rat monoclonal antibodies. VII. Enhancement of ascites production and yield of monoclonal antibodies in rats following pretreatment with pristane and Freund's adjuvant.
The effect of intraperitoneal injections of pristane, incomplete Freund's adjuvant (IFA) and a v/v mixture of pristane and IFA (called PIFA) on ascites production and the yield of monoclonal antibodies has been studied in Louvain rats. The best results were obtained following injection of 2 ml PIFA at the moment of i.p. transfer of hybridoma or immunocytoma cells. Ascites production was increased by as much as 4.7 times and monoclonal antibody production by more than six times compared with untreated control rats.
Animals↗
An analysis of the inhibition of replication of HIV and MuLV by some 3'-blocked pyrimidine analogs.
Some 3'-blocked pyrimidine analogs were synthesized and tested as inhibitors of replication of human immunodeficiency virus (HIV) and Moloney-murine leukemia virus (MuLV). The analogs were of 3 kinds: (1) analogs of 3'-azido-3'-deoxythymidine (AZT) in which the C-5 CH3 of the base was exchanged for H (AZU) or C2H5 (AZEU); (2) 3'-fluoro-3'-deoxythymidine (FLT) and analogs thereof, in which the C-5 CH3 of the base was exchanged for H (FLU), C2H5 (FLEU) or nC3H7 (FLPU); (3) the threo analogs of AZT (AZT increases) and AZU (AZU increases). All analogs were less active inhibitors of HIV replication than AZT, except FLT, which was as active as AZT. The 3'-fluoro analogs and AZEU did not inhibit MuLV replication at non-cytotoxic concentrations. Oral administration of FLT to MuLV-infected mice result in antiviral effects only at toxic drug levels. AZU and FLU were less potent inhibitors of HIV replication than AZT or FLT, but the 2'-deoxy uridine analogs were less cytotoxic to human embryonic fibroblasts than the thymidine analogs. The 5'-triphosphates of AZU, AZT, AZEU, FLT and FLEU were tested as inhibitors of the HIV- and MuLV-reverse transcriptases. Ranking of the Ki/Km values for HIV-RT resulted in the following order of potency of the 5'-triphosphates AZT = FLT greater than AZU greater than AZEU greater than FLEU. The 5'-triphosphates of AZEU, FLT and FLEU did not inhibit the MuLV-RT, which explains, in part, the lack of effect of these analogs against MuLV replication. The threo forms (azido "up") of AZU and AZT were less active inhibitors of HIV replication than the erythro forms (azido "down"). A 15N-NMR and 1H-NMR study showed that the furanose moieties of analogs with the azido function "up" assume a conformation distinct from that of the analogs with azido "down". This is due to intramolecular stabilisation of the "N" conformer in the threo ("up") diastereomer, due to interaction of the azido functions with the nucleobase and possibly the OH group of C-5' of the furanose. As discussed, this conformation might explain the decreased biological activity of threo forms compared with the erythro forms.
Animals↗
Total and specific IgE in serum and cerebrospinal fluid of rats and guinea pigs infected with Angiostrongylus cantonensis.
The total and specific IgE response to Angiostrongylus cantonensis infection was evaluated according to host permissiveness. Total IgE levels measured by a double antibody radioimmunoassay (RIA) increased slowly in the permissive host (the rat), reaching a maximum between 4 and 8 weeks after infection. This maximum was earlier but significantly lower in the non-permissive host (the guinea pig). IgE antibodies specific for adult worms or L1 or L3 larvae of A. cantonensis were measured by a radioallergosorbent test (RAST). In the case of adult worms and L1 antigens, specific IgE antibody levels showed large variations in relation to the duration of infection in rats. In contrast to total IgE levels, the specific IgE response to L3 larvae was lower in rats than in guinea pigs in both the serum and cerebrospinal fluid (CSF). These results suggest variations in the total vs specific IgE response according to host permissiveness or non-permissiveness to A. cantonensis infection. These results are discussed in the context of the possible participation of IgE antibodies in immune defence.
Angiostrongylus↗
Control of IgE responses.
Peyer's patches (PP) in germ-free rats (GF) and in the hyper-IgE syndrome patient (HIES) differ from their conventional rat (C) and healthy human (HH) counterparts in that GF rats contained fewer (two-fold) PP and none was detected in HIES. Existing PP in GF rats had reduced cellularity (three-fold) and different B and T cell subsets: high numbers of IgE-bearing (sIgE+) B cells (approximately 15% of total cells), one-half of which also expressed sIgA, were present in GF rat PP while none was detected in C rat PP (less than 1%). GF rat PP also contained elevated numbers of sIgA+ cells and decreased sIgM+ cells, with elevated numbers of sThy 1+ RT 7.1+ Ig- T cells (suppressor phenotype) and reduced sThy 1- RT 7.1+ Ig- T cells (helper phenotype). The cellular composition of GF rat PP was converted to that resembling a C rat within 18 hr after (a) use of standard (unautoclaved) chow; (b) feeding with certain bacteria or "working" bacterial cell wall components (BCWC) and synthetic derivatives, murein, MTP-PE, and norMDP, but not with LPS, core lipid A, or lipoprotein; BCWC had no effect if injected intravenously; or (c) thymectomy. Each procedure resulted in (i) elimination of sIgE+ B cells and normalization of the other isotypes, and (ii) loss of T suppressor cells and normalization of T helper cells. After treatments, no sIgE+ cells were detected in bone marrow (BM), thymus, other lymphoid organs, or blood. PP were not detected in HIES, although they were present in HH (approximately 10/individual). P blood contained two distinct sIgE+ B cell subpopulations, the apparent source of which was mesenteric lymph node (MLN), the only organ in which high numbers of these cells (35%) (five nodes examined) were detected; far fewer IgE+ cells were found in spleen (less than 5%), and none was detected in BM, thymus, other LN, or appendix, which was virtually acellular. Virtually no IgE secreting plasma cells were detected in MLN, spleen, appendix, other lymphoid organs, or in gut lamina propria. IgE+ B cells in MLN were not detected in follicles (classical B cell areas); instead, they were found in high numbers in the thymus-dependent area and in medulla. Most follicles (greater than 98%) in MLN and spleen contained intercellular IgE complexed to bacterial antigen and/or CD23 (IgE-binding factor? antigen?), but contained no germinal centers.(ABSTRACT TRUNCATED AT 400 WORDS)
Adult↗
Isolation and characterization of a VH domain fragment from monoclonal rat IgG of IgG1 and IgG2a subclasses.
Digestion with trypsin of monoclonal rat IgG of IgG1 and IgG2a subclasses produced two fragments, isolated only in dissociating media. The larger fragment (mol. wt. 120,000 Da) was comprised of the two light chains covalently bound to shortened gamma chains. Amino acid sequence of the shortened gamma chain indicated that the site of cleavage is located at the beginning of the C gamma 1 domain at a position homologous to residue 139 of mouse gamma heavy chain of IgG1 MOPC 21. The smaller fragment (mol. wt. 13,000 Da) was found to consist of the entire variable domain of the heavy chain and probably a short stretch of the C gamma 1 domain. The unique susceptibility of rat monoclonal IgG1 and IgG2a is likely to be the result of the presence of a lysine residue in a loop of C gamma 1 domain, which therefore is accessible to trypsin. Tryptic cleavage of rat monoclonal antibodies of IgG1 and IgG2a subclasses can be considered as a simple method to produce a fragment related to the VH domain.
Amino Acid Sequence↗
Failure to detect immune deficiency in rats after prenatal or early postnatal irradiation.
We have looked for medium-term sequelae in the immune system of rats that had been X-irradiated (0-2 Gy whole-body irradiation) during prenatal or early postnatal life. At an age of 8 weeks the histology of the spleen was normal, and so was the distribution of B and T lymphocytes. The serum immunoglobulin levels were not significantly altered, even when the different isotypes were considered. At an age of 10 weeks, the rats were immunized with a T-dependent or a T-independent dinitrophenylated-carrier antigen. Normal levels of specific antibodies were generated in all groups of animals injected with the T-independent antigen. The T-dependent response, in contrast, was higher in animals irradiated between day 6 and day 20 of gestation (but not in rats irradiated early after birth). This increase, however, was significant only for the IgM and IgG1 responses of some irradiated groups. Thus no medium-term immunodeficiency could be documented with the methods used. The alteration in a T-dependent response, however, points to a radiosensitive T regulatory mechanism.
Animals↗
Chemotactic properties of rat immunoglobulins and immune complexes.
The effect of rat immunoglobulins and immune complexes on the locomotor function of rat polymorphonuclear leukocytes (PMN) was investigated in vitro. Rat immunoglobulin G1 (IgG1), IgG2a, IgG2b, and IgA monoclonal antibodies specific for the dinitrophenyl hapten were used. Both monomeric and polymeric IgA showed chemotactic activity in a dose-dependent manner. IgG1 and IgG2b also induced a dose-dependent locomotor response of PMN, but the nature of the induced migration was chemokinetic (enhancing random migration). IgG2a was chemotactic and induced maximal migration at a relatively low concentration. IgG1- and IgG2b-immune complexes induced stronger migration than antibody alone; however, IgA- and IgG2a-immune complexes did not. IgA was shown to modify the chemotactic movement of PMN induced by N-formylmethionyl-leucyl-phenylalanine (FMLP). In the presence of both IgA and FMLP in the lower chamber, the migration towards suboptimal concentrations of FMLP was enhanced. By contrast, IgA in the upper chamber decreased migration towards the optimal or higher concentrations of FMLP. These findings suggest that IgA may work synergistically with luminal chemoattractants to mobilize PMN to the locus of infection on the mucosal surface. In addition, the intense activity of IgG2a alone and IgG1- or IgG2b-immune complexes in inducing PMN migration may play an important role in inflammatory processes. The data indicate that immunoglobulins have a direct effect on PMN mobility.
Animals↗
Rat monoclonal antibodies to human apolipoprotein B: advantages and applications.
Eight monoclonal antibodies (Mabs) to human serum low density lipoprotein (LDL) were derived from the fusion of spleen cells, from LOU rats immunized with human LDL, and the rat myeloma line IR983F. These Mabs were characterized in terms of isotype, specificity, and affinity. Competitive experiments indicated that the epitopes that were recognized could be grouped into three patterns depending on their apparent affinity for apoB-containing lipoprotein particles such as LDL, very low density lipoproteins (VLDL), or intermediate density lipoproteins (IDL). Six epitopes have been mapped in relation to elements of the sequence of apolipoprotein B-100 (apoB-100) and some have been assigned to the middle part of the median thrombolytic fragment T3, a region not yet well targeted by mouse Mabs. The presence of lipids for the expression of the epitopes was studied and confirmed a lipid dependence for epitopes that are close to the T2/T3 cleavage site. The capacity of binding to the LDL receptor was also tested; among the Mabs we described, one inhibited the uptake and degradation of LDL to HeLa cells receptor. Finally, some antibodies were able to precipitate LDL in gel.
Animals↗
IgE-mediated release of rat mast cell protease II, beta-hexosaminidase and leukotriene C4 from cultured bone marrow-derived rat mast cells.
Functional characteristics of cultured bone marrow-derived rat mast cells (BMMC) were studied. BMMC were shown to release in a time- and dose-dependent fashion the mucosal mast cell (MMC)-specific enzyme, rat mast cell protease II (RMCPII), following IgE-mediated activation in vitro. RMCPII release was temporally associated with that of the mast cell granule-derived enzyme, beta-hexosaminidase (beta-hex). Release of the pre-formed granule constituents, RMCPII and beta-hex, was associated with the generation of the membrane-derived lipid mediator, leukotriene C4 (LTC4) and, in older cultures, substantial amounts were generated (25.2 ng/10(6) BMMC). Absolute amounts of RMCPII, beta-hex and LTC4 released were dependent upon the age of the BMMC. These results extend our previous observations on the staining properties and protease content of rat BMMC and provide evidence that these cells are functionally, as well as histochemically, analogous to the MMC subset, which is so prominent during intestinal nematode infections in rats.
Animals↗
[Immunohistochemical analysis of splenic tissue in rats with destruction of the hypothalamic structures].
The immunoenzyme histochemical technique to stain the IgM- and IgD-bearing cells was used to study the morphometric characteristics of B-lymphocyte-dependent zones in spleen white pulp of Wistar rats (intact, sham operated and after cortex or hypothalamic lesions). In the groups of sham-operated and cortex-lesioned rats it has been shown the increase of spleen weight 7 days after the operation due to the increase of the red pulp weight. The white pulp compartment's ratio is not affected. Lesioning of the posterior hypothalamic area prevents these effects of the operation, while local coagulation of the lateral hypothalamic area causes a significant decrease of the weight of spleen primary follicules which contain IgM+IgD+-bearing B-lymphocytes exerting characteristics of circulating pool of B-lymphocytes. These data are in favour of the CNS participation in regulation of B-lymphocyte migratory activity.
Animals↗
Adoptive T cell transfer of autoimmune nonobese diabetic mouse diabetes does not require recruitment of host B lymphocytes.
The autoimmune nonobese diabetic mouse, a model of human juvenile type I diabetes mellitus, exhibits features of both B and T cell autoreactivity against insulin-producing cells. Using the neonatal cell transfer model of the disease, which we have described previously, we have shown that B cell suppression of newborn recipients by anti-mu treatment did not affect the transfer of diabetes by means of T cells. B cell-depleted, purified T cells from diabetic adults were injected into newborns treated with either IR-52, a control rat myeloma protein, or LOMM.9, a rat anti-mouse mu-chain mAb. Both groups developed diabetes over a similar time scale. Although the pancreases in both groups showed massive infiltration by T lymphocytes, B lymphocytes, presumably recruited in the host, were present in the IR-52-treated group, whereas they were absent in the LOMM.9-treated group. Anti-mu-treated diabetic animals showed substantial B cell suppression in vivo and in vitro when compared with IR-52-treated controls. These results suggest that B cell autoreactivity is a secondary phenomenon that is unimportant during the effector phase of diabetes in nonobese diabetic mice.
Animals↗
Activation of rat complement by soluble and insoluble rat IgA immune complexes.
The ability of rat monoclonal IgA, specific for 2,4-dinitrophenyl (DNA), to activate the complement (C) system of the rat was investigated using aggregated IgA or IgA immune complexes (IC). IgA was coated onto a solid phase, and tested for its capacity to bind C3 upon incubation at 37 degrees C in normal rat serum (NRS) in the presence of Mg-EGTA. Binding of C3 was observed dependent on the dose of dimeric (d-), polymeric (p-) and secretory IgA tested. In contrast, little C3 fixation was observed in this system with monomeric (m-) rat IgA or with mouse m- and d-IgA (MOPC315). Soluble and insoluble rat IgA IC were prepared using dinitrophenylated rat serum albumin (DNP8RSA) as antigen (Ag), and assessed for C activation. It was shown that insoluble IC (immune precipitates; IP) containing m-, d- or pIgA of rat origin activate the alternative pathway of rat C, as demonstrated by their capacity to induce C consumption in NRS in the presence of Mg-EGTA. When p- and m-IgA IP were compared for their capacity to activate C, it was found that p-IgA activated C four times as efficiently as m-IgA IP (at 2 mg/ml). Soluble rat IgA IC were prepared in an excess of DNP8RSA, fractionated by gel filtration on Sepharose 6B, and analyzed for C activation and antibody (Ab)/Ag ratio. In contrast to m-IgA IP, soluble m-IgA did not activate C. On the other hand soluble d-IgA IC activated C dependent on their concentration and size: at a concentration of 0.1 mg/ml high-molecular weight d-IgA IC with a high Ab/Ag ratio were four times as efficient as low-molecular weight IC with a low Ab/Ag ratio, and twice as efficient as IP prepared at equivalence. To demonstrate the induction by IgA of the assembly of the terminal membrane attack complex, trinitrophenyl (TNP)-conjugated rat red blood cells (TNP-RRBC) coated with d- or p-IgA were shown to be lysed in NRS in the presence of Mg-EGTA. No lysis of m-IgA-coated TNP-RRBC was observed. The results in this study demonstrate that both soluble and insoluble rat IgA IC activate the alternative pathway of homologous rat C. Alternative pathway activation by soluble rate IgA IC is dependent on the size of the IC. The degree of polymerization of the IgA Ab itself also influences C activation.
Animals↗
Anti-Listeria monocytogenes immunity in mu-suppressed mice: a comparison of treatment with conventional hyperimmune rabbit anti-mouse IgM and affinity-purified, monoclonal rat anti-mouse IgM.
The capacity of anti-IgM treated, B-cell-depleted mice to control infection by Listeria monocytogenes was evaluated. Suppression was achieved with a hyperimmune rabbit anti-mouse-IgM antiserum (IRS), with affinity-purified IRS (IRP), or with an affinity-purified, monoclonal, rat anti-mouse-IgM antibody (LO-MM-9). B-cell depletion in specifically treated mice was judged to be complete by the following criteria: absence of significant response to a B-cell mitogen lipopolysaccharide, absence of B-cells with detectable IgM or kappa light chain on their surface, absence of detectable IgM, and presence of free anti-IgM antibodies in serum. BALB/c mice, conventionally treated from birth with IRS, had an increased capacity to clear L. monocytogenes from the blood during the first 5 min after intravenous infection. Furthermore, control of infection seemed to be enhanced during the first 24 h but was found to be impaired when assessed 3 and 4 days after initiation of infection. These effects were, however, not IRS specific, because control mice treated with normal rabbit serum behaved comparably. Mortality caused by 2 x 10(3) L. monocytogenes injected intraperitoneally into BALB/c mice susceptible to L. monocytogenes was increased more in NRS-than in IRS-treated mice when both were compared with untreated control mice. Therefore, chronic injection of IRS or NRS seemed to disturb anti-L. monocytogenes immunity, rendering an evaluation of the role of antibodies impossible.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Immunoglobulin A receptor of rat small intestinal enterocytes is unaffected by aging.
The receptor for polymeric immunoglobulins is responsible for the transport of immunoglobulin A (IgA) through epithelial cells and its subsequent delivery to mucosal surfaces. We have extended our previous studies of the IgA receptor in the liver of the aging Fischer rat to include the small intestine. Basolateral membrane-enriched fractions prepared from rat small intestinal enterocytes exhibit a single binding site for dimeric IgA. This receptor is specific for molecules that interact with rat secretory component, e.g., rat dimeric IgA and IgM and human polymeric IgA but not human monomeric IgA or rat secretory IgA. Inhibition of binding by rabbit-antirat secretory component also indicated that binding is specific for secretory component. Both liver and intestinal membranes showed virtually identical binding specificity. Membranes from crypt cells show increased IgA binding (320 fmol bound per milligram protein) compared with villous cells (105 fmol bound per milligram protein); however, other than increased binding, crypt cells show the same binding characteristics as villous cells. In contrast to our previous findings, in which liver plasma membranes from old rats showed a four-fold decrease in IgA binding compared with young adult rats, membrane fractions from rat enterocytes showed no alterations in dimeric IgA binding with increased age.
Aging↗