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J P Vaerman

Publications and source records attributed to J P Vaerman.

At least 37 records · Page 2Linked to original sources
PubMed1996

Evaluation of monoclonal antibodies with specificity for human IgA, IgA subclasses and allotypes and secretory component. Results of an IUIS/WHO collaborative study.

51 monoclonal antibodies (McAb) with putative specificity for human IgA, the IgA subclasses, Am allotypes or secretory component (SC) were evaluated for immunoreactivity and specificity by nine laboratories employing immunodiffusion, agglutination, immunohistological assays, immunoblotting and direct binding and competitive inhibition enzyme immunoassays. McAbs specific for IgA PAN (n = 24), IgA1 (n = 7), IgA2 (n = 3), IgA2m(2) (n = 2), non-IgA2m(2) (n = 4) and SC or secretory IgA (n = 5) were identified that were immunoreactive and specific in the assays employed. The McAbs identified as IgA- or SC-reactive were shown to be non-reactive to human IgG, IgM, IgD, IgE, kappa and lambda by direct binding and competitive inhibition immunoassays. Interestingly, no McAbs with restricted specificity for IgA2m(1) were identified. Some McAbs displayed higher affinity and/or better performance in one or several of the assay groups. The IgA- and SC-specific McAbs identified in this international collaborative study have potential as immunochemical reference reagents to identify and quantitate monomeric and polymeric IgA in human serum and secretions.

Animals↗
PubMed1996

Effect of intrajejunal elemental diet perfusion on local secretion of soluble CD4 and CD8.

The effects of nutrients on the mucosal immune system are poorly understood. The aim of this work was to study the cellular mucosal immune response to intrajejunal perfusion of an elemental diet (ED) or a control (C) electrolyte solution by measuring jejunal secretion of soluble CD4 (sCD4) and sCD8. sCD4 and sCD8 are markers of helper/inducer and suppressor/cytotoxic regulatory functions of T cells, respectively. A four lumen tube with a proximal occluding balloon at the angle of Treitz was used for jejunal perfusion in seven healthy volunteers (mean age 23 years). The length of the test segment was 40 cm. The jejunum was successively perfused with C for 80 min and then with ED containing 21.3 g/l of free amino acids and 104.2 g/l of oligosaccharides for 100 min. Jejunal fluid and serum concentrations of sCD4 and sCD8 were measured and their jejunal outputs calculated. When compared with C perfusion, jejunal perfusion with the ED resulted in a significant increase of sCD8 but not sCD4 jejunal secretion rates. sCD8 jejunal values increased early after ED perfusion and stayed at roughly the same level during the perfusion. Serum concentrations of sCD4 and sCD8 were not modified during ED perfusion. These data support the hypothesis that ED suppresses the immunologic tone of the gut, which could explain its beneficial effect in the management of intestinal inflammatory disease.

Adult↗
PubMed1996

The transcytotic pathway of an apical plasma membrane protein (B10) in hepatocytes is similar to that of IgA and occurs via a tubular pericentriolar compartment.

In hepatocytes, newly synthesized apical plasma membrane proteins are first delivered to the basolateral surface and are supposed to reach the apical surface by transcytosis. The transcytotic pathway of apical membrane proteins and its relationship with other endosomal pathways has not been demonstrated morphologically. We compared the intracellular route of an apical plasma membrane protein, B10, with that of polymeric IgA (pIgA), which is transcytosed, transferrin (Tf) which is recycled, and asialoorosomucoid (ASOR) which is delivered to lysosomes. Ligands and anti-B10 monoclonal IgG were linked to fluorochromes or with peroxidase. The fate of each ligand was followed by confocal and electron microscopy in polarized primary monolayers of rat hepatocytes. When fluorescent anti-B10 IgG and fluorescent pIgA were simultaneously endocytosed for 15-30 minutes, they both uniformly labelled a juxtanuclear compartment. By 30-60 minutes, they reached the bile canaliculi. Tf and ASOR were also routed to the juxtanuclear area, but their fluorescence patterns were more punctate. Microtubule disruption prevented all ligands from reaching the juxtanuclear area. This area corresponded, at least partially, to the localization of the mannose 6-phosphate receptor, an endosomal marker. By electron microscopy, the juxtanuclear compartment was made up of anastomosing tubules connected to vacuoles, and was organized around the centrioles. B10 and pIgA were mainly found in the tubules, whereas ASOR was segregated inside the vacuolar elements and Tf within thinner, recycling tubules. In conclusion, transcytosis of the apical membrane protein B10 occurs inside tubules similar to those carrying pIgA, and involves passage via the pericentriolar area. In the pericentriolar area, the transcytotic tubules appear to maintain connections with other endosomal elements where sorting between recycled and degraded ligands occurs.

Animals↗
PubMed1995

Dimeric and tetrameric IgA are transcytosed equally by the polymeric Ig receptor.

Polymeric IgA (pIgA) is transcytosed across epithelial cells and into external secretions by the polymeric Ig receptor (pIgR). Binding of dimeric IgA (dIgA) to the pIgR stimulates transcytosis of the pIgR. The pIgA in secretions is found as dimers (dIgA) and higher polymers, such as tetramers (tIgA), but little is known of the functional significance of the different sizes. Here we compared the ability of dIgA and tIgA to perform three functions that are essential to their transport into mucosal secretions. 1) Equilibrium binding studies showed that there were twice as many binding sites for tIgA as dIgA at the basolateral cell surface, but that the affinity of these sites for tIgA was one-half of that for dIgA. 2) Both dIgA and tIgA were rapidly transcytosed by the pIgR, although transcytosis of tIgA was slower. 3) Both dIgA and tIgA could stimulate transcytosis of the pIgR, although tIgA was less effective. The possible implications of these findings for the relative biologic roles of dIgA and tIgA are discussed.

Animals↗
PubMed1995

Secretion of immunoglobulins and plasma proteins from the colonic mucosa: an in vivo study in man.

There are no available data on immunoglobulins and albumin outputs into the normal human colon. We thus measured the intracolonic secretion rates of IgA, IgG, IgM, secretory component (SC) and plasma proteins (albumin (Alb), orosomucoid (Oro), transferrin (Transf) and alpha 2-macroglobulin (alpha 2-M)). Using a pancolonic perfusion technique in 10 healthy volunteers (six females, four males, mean age 24 years), concentrations and outputs of Alb, immunoglobulins, SC, Oro, Transf and alpha 2-M were measured in the rectal effluents by immunoradiometric assay. Monomeric (m) and polymeric (p) IgA distribution was analysed by sucrose density ultracentrifugation. The secretion of polymeric IgA (p-IgA) was 153 micrograms/min, i.e. 220 mg/day, exceeding that of other immunoglobulins (m-IgA 8.5 micrograms/min; IgG 33.5 micrograms/min; IgM 17 micrograms/min) and of non-immunoglobulin proteins (Alb 104 micrograms/min; Oro 9 micrograms/min; Transf 7 micrograms/min; alpha 2-M 4.5 micrograms/min). p-IgA was entirely linked to SC (secretory IgA) and 12% of SC was in free form. About 62% of total IgA was IgA2. For each protein, a relative coefficient of excretion (RCE) was calculated (colon to serum concentration ratio expressed relative to that of Alb). The p-IgA, IgM and m-IgA RCE were 277, 6 and 2.2 times higher than the values predicted from their molecular weight. RCE of non-immunoglobulin proteins also exceeded the values expected from a passive seepage from the vascular compartment. The intracolonic clearance of Alb extrapolated to 24 h was only 3.7 ml/day. These results show the high local production and/or the facilitated transport to the colonic lumen of p-IgA, and are in very good agreement with the distribution of plasma cells in the colonic mucosa.

Adult↗
PubMed1995

Homogenous IgA monomers, dimers, trimers and tetramers from the same IgA myeloma serum.

Starting from two IgA1 myeloma sera, the isolation of monoclonal monomeric, dimeric, trimeric and tetrameric IgA in a high state of purity and size homogeneity for each serum is described. The method combined repetitive gel filtrations on Ultrogel AcA22 with affinity chromatography on Jacalin-Sepharose. These various forms of pure polymeric IgA obtained from the same monoclonal IgA should allow a precise comparison of their respective structure and reactivity with different IgA-binding proteins, such as IgA Fc-receptors, the polymeric Ig receptor, and lectins.

Antibodies, Monoclonal↗
PubMed1994

Stimulation of transcytosis of the polymeric immunoglobulin receptor by dimeric IgA.

The polymeric immunoglobulin receptor (pIgR) is transcytosed from the basolateral to the apical surface of polarized epithelial cells. We have previously shown that phosphorylation of Ser-664 in the cytoplasmic domain of the pIgR is a signal for its transcytosis. We now report that binding of a physiological ligand, dimeric IgA, to pIgR stimulates pIgR transcytosis. This stimulation occurs in both the presence or absence of Ser-664 phosphorylation. We have used three methods to measure transcytosis of the pIgR. (i) The pIgR was biosynthetically labeled and its cleavage to secretory component after transcytosis was measured. (ii) The pIgR was labeled with biotin at the basolateral surface. After transcytosis, release of the biotin-labeled secretory component into the apical medium was measured. (iii) Transcytosis of a ligand bound to the pIgR was measured. All three methods indicated that dimeric IgA stimulates transcytosis of the pIgR.

Animals↗
PubMed1994

Validation of IgA1 and IgA2 measurements by a solid-phase immunoradiometric assay in serum and secretions.

We describe specific, sensitive and reproducible immunoradiometric assays to measure total IgA and IgA subclass levels in biological fluids, which take into account the problem that polymeric forms are differently recognized in immunoassays. Sera from subjects totally deficient in one of the IgA subclasses allowed us to ensure the specificity of the subclass assays and to define the proportions of IgA1 (84%) and IgA2 (16%) in the normal pooled serum (from 30 blood donors) used as standard. With purified milk 11-S secretory IgA1 and 11-S secretory IgA2, we determined a correction factor for the corresponding polymeric forms using, respectively, monomeric IgA1 and monomeric IgA2 from pooled serum as standards. With the monoclonal antibodies used, purified 11-S secretory IgA1 was similarly recognized by both the total IgA assay and the IgA1 assay; both total IgA and IgA1 concentrations were underestimated compared with monomeric IgA or monomeric IgA1. In contrast, 11-S secretory IgA2 was better recognized by the IgA2 assay than by the total IgA assay and the values were thus overestimates. Considering this problem of recognition, we fractionated saliva and lung secretions by sucrose density gradient ultracentrifugation before measuring their IgA1 and IgA2 levels.

Adult↗
PubMed1994

Interaction between streptococcal protein Arp and different molecular forms of human immunoglobulin A.

Protein Arp, the IgA-binding protein of the group A Streptococcus, has affinity for the Fc-part of IgA. The binding between protein Arp and several different molecular forms of human IgA was characterized. It was found that protein Arp bound with higher affinity to uncomplexed forms of IgA than to complexed forms (secretory IgA, alpha 1-antitrypsin-IgA and alpha 1-microglobulin-IgA). Thus, the affinity constant was 2.0-5.9 x 10(8) M-1 for the binding to monomeric, dimeric, trimeric, and quadrimeric IgA, and 4.5-5.0 x 10(7) M-1 for binding to the complexed forms. Among the uncomplexed IgA-molecules, the affinity constant was in the same range for J chain-containing forms (dimeric, trimeric and quadrimeric IgA) as for forms without J chain (monomeric and a particular quadrimeric IgA devoid of J chain). Western blotting demonstrated that protein Arp bound exclusively to the alpha-chain of all IgA-forms. Several lines of evidence pointed to a localization of the binding site to the C alpha 3-domain. First, protein Arp did not bind to three N-terminal alpha-chain fragments which lacked a region corresponding to the C alpha 3-domain, including that form a four-chain myeloma IgA, naturally occurring in plasma. Second, the binding to dimeric and tri/quadrimeric IgA was partially blocked by an added secretory component, which has been suggested to bind to the C alpha 2- and C alpha 3-domains of the alpha-chain. Finally, alpha 1-antitrypsin and alpha 1-microglobulin, in the weakly binding IgA-complexes, have been shown to be linked to the C alpha 3-domain via the penultimate amino acid residue of the alpha-chain peptide, supporting the hypothesis of a localization of the binding site of protein Arp to the C alpha 3-domain.

Bacterial Proteins↗
PubMed1994

Human antibody response to Clostridium difficile toxin A in relation to clinical course of infection.

This study investigated whether differences in fecal and serum antitoxin A antibody levels may account for the duration of Clostridium difficile-associated diarrhea (CDAD) and the occurrence of relapses. By an enzyme linked-immunosorbent assay, we tested 40 patients with CDAD including 25 patients without immunodeficiency and 15 patients receiving antineoplastic drugs. Two hundred eighty serum samples and 80 normal stool samples were investigated as controls. In nonimmunocompromised patients, serum immunoglobulin (IgG) and fecal IgA antitoxin A antibody titers were significantly higher in patients who suffered a single episode (n = 21) than in those with relapsing CDAD (n = 4) whose titers were at control levels. Of these 25 patients, eight suffered from diarrhea which lasted for more than 2 weeks. These patients had significantly lower serum- and feces-specific antibody levels than the others who presented symptoms of shorter duration. In cytostatic-treated patients, antitoxin A antibody levels were similar to controls, but relapses occurred in a single case. These data suggest an association between a defective humoral response to toxin A and a more severe form of C. difficile infection. They also indicate that other host-related factors control the severity of CDAD and remain to be elucidated.

Adolescent↗