Biomedical subjects

J P Vaerman

Publications and source records attributed to J P Vaerman.

At least 73 records · Page 4Linked to original sources

PubMed1991

Jejunal immunoglobulin secretion in alcoholic patients with and without cirrhosis.

Alcoholic liver diseases are associated with an elevation of serum immunoglobulin A (IgA). This could be the result of increased IgA production by the intestinal mucosa. Serum and jejunal immunoglobulin, albumin and orosomucoid were measured in 13 alcoholic patients with (n = 6) and without (n = 7) cirrhosis and compared to 11 controls. Jejunal secretions were obtained by segmental perfusion under an occluding balloon. High levels of serum monomeric and polymeric IgA were only found in patients with cirrhosis. Alcoholics with and without cirrhosis had normal monomeric and polymeric IgA jejunal secretion rates. jejunal clearances of albumin, orosomucoid and immunoglobulin G were significantly higher in both non-cirrhotic and cirrhotic patients than in controls. These findings indicate normal jejunal IgA secretion and increased permeability to plasma proteins, such as albumin and immunoglobulin G in alcoholics.

Adult↗

PubMed1991

Protection of rat intestine against cholera toxin challenge by monoclonal anti-idiotypic antibody immunization via enteral and parenteral routes.

A mouse monoclonal anti-idiotypic (anti-id) immunoglobulin M (IgM) antibody, called MAb2, was raised against a mouse monoclonal anti-cholera toxin (anti-CT) antibody (MAb1). The MAb2 was shown, by competition with CT for MAb1, to bear the internal image of an epitope of CT. MAb2 immunization of rats was performed via the intraperitoneal, intragastric, and intrajejunal routes and compared with immunization of rats with either a control, isotype- and allotype-matched MAb or with CT via the same routes. Both serum IgG and bile IgA anti-CT Ab3's were detected by enzyme-linked immunosorbent assay in anti-id MAb2-immunized rats, although their titers were lower than those in CT-immunized rats. No anti-CT antibodies were detected in sera and bile of rats immunized with the control MAb. When tested for degree of gut protection against a CT challenge, rats immunized with MAb2 by the intrajejunal route showed a rather high degree of protection, which was only slightly lower than that of rats immunized with CT via the same route; all rats but one immunized with the control MAb were unprotected. There was, however, no correlation between serum or bile anti-CT titers and degree of gut protection in MAb2-immunized rats. Their serum anti-CT Ab3's were purified by adsorption and elution from a CT immunosorbent and resembled anti-CT MAb1 in their unique reactivity with MAb2. This constitutes to our knowledge the second report of protection against a pathogen by anti-id immunization via the enteric route.

Animals↗

PubMed1991

Antiglomerular basement membrane nephritis induced by IgA1 antibodies.

A 62-year-old man was admitted for acute renal failure due to crescentic rapidly progressive glomerulonephritis. Kidney biopsy showed intense staining for IgA, IgA1 and C3 in a linear pattern along the glomerular basement membrane (GBM). Serologic tests for detecting anti-GBM antibodies were positive for IgA class and IgA1 subclass and negative for IgG and IgA2. Serum IgA anti-GBM antibodies appeared essentially in the polymeric form, an observation in agreement with recent studies demonstrating polymeric IgA response after parenteral immunization. There was no sign of pulmonary involvement. This patient is the first to present with an isolated nephritis due to anti-GBM antibodies restricted to the IgA class (IgA1 subclass). Routine tests for circulating anti-GBM antibodies should also include the IgA class.

Acute Kidney Injury↗

PubMed1991

[Jejunal secretion of immunoglobulins and secretory component in three patients with primitive humoral immunoglobulin deficiency].

Jejunal secretion of albumin, immunoglobulins and secretory component was studied using the segmental perfusion technique with an occluding balloon, in two patients with common variable hypogammaglobulinemia and one patient with selective immunoglobulin A deficiency. Results were compared with those of twenty-two controls previously studied under the same conditions. In all three cases, jejunal secretion rate of immunoglobulin A was nil and secretion rates of albumin and immunoglobulin G were increased as compared to controls. Jejunal secretion rate of immunoglobulin M was increased in the patient with selective immunoglobulin A deficiency, normal in one case of common variable hypogammaglobulinemia and almost nil in the other case. Secretory component was secreted in the jejunal lumen mostly or exclusively under a free form depending on partial or total absence of immunoglobulin A and M. This study allowed to confirm in vivo that secretion of secretory component is independent of the presence of immunoglobulins. Intestinal perfusion might be a useful tool in the investigation of immunological diseases of the intestinal tract.

Adult↗

PubMed1991

IgA triggers tumor necrosis factor alpha secretion by monocytes: a study in normal subjects and patients with alcoholic cirrhosis.

Under endotoxin-free conditions, peripheral blood mononuclear cells and purified monocytes isolated from healthy control subjects and patients with alcoholic cirrhosis disclose elevated tumor necrosis factor alpha messenger RNA level and produce tumor necrosis factor alpha in response to stimulation by either soluble polymeric IgA or monomeric IgA bound to the surface of culture dishes but not by soluble monomeric IgA. Polymeric IgA induces tumor necrosis factor alpha secretion in a dose-dependent fashion. These results suggest that cross-linking of Fc alpha receptors on human monocytes induces the messenger RNA accumulation and the secretion of the cytotoxic and immunoregulatory cytokine tumor necrosis factor alpha. Furthermore, it is shown that lipopolysaccharide-induced tumor necrosis factor alpha secretion by peripheral blood mononuclear cells is synergistically enhanced in the presence of solid phase monomeric IgA but not in the presence of either soluble monomeric or polymeric IgA. Although increased lipopolysaccharide-induced tumor necrosis factor alpha secretion is observed at baseline in alcoholic cirrhotic patients, this synergism is also expressed in this group of patients. These observations could be of pathophysiological relevance in alcoholic cirrhosis because monomeric IgA deposits along the liver sinusoids and increased serum levels of polymeric IgA are common even in the early stages of this disease.

Female↗

PubMed1991

Extrahepatic bile duct growth in mice repeatedly injected with human normal serum, IgA-deficient serum or purified secretory IgA.

Another group of researchers has reported that seven intraperitoneal injections into mice of purified human serum IgA or normal human serum--but not IgA-deficient serum, mouse serum or saline--induced considerable growth of the extrahepatic bile duct epithelium. They stated that heterologous IgA was principally responsible for this effect. We have quantitated this growth by another method: enumeration of total and radiolabeled nuclei of the lumenal and glandular epithelium in transverse duct sections after tritiated thymidine injection and autoradiography. Our data show maximal incorporation between 18 and 24 hr after the last injection, with the highest labeling index in the lumenal epithelium after only three injections and before any duct enlargement. After four to seven injections, thymidine incorporation continued in juxtalumenal glands, together with massive glandular proliferation into the thickening wall and obvious inflammation. These changes were more pronounced in the liver-proximal part of the duct without affecting intrahepatic duct and gallbladder epithelia. Subcutaneous serum injections were less active. We confirm the inactivity of buffered saline, but, unlike previous authors, demonstrate strong activity in purified human milk secretory IgA and in IgA-deficient serum. We suggest that this different approach of quantitating epithelial proliferation will allow comparison of the bile duct growth effects of different, well-characterized human and animal IgA preparations.

Animals↗

PubMed1990

Androgen regulation of secretory component synthesis by lacrimal gland acinar cells in vitro.

This study sought to determine whether androgens directly stimulate the production of secretory component (SC) by acinar cells from the rat lacrimal gland. Homogeneous populations of acrinar cells were isolated from lacrimal tissues by serial enzymatic digestion and Ficoll gradient centrifugation and then cultured on reconstituted basement membranes in supplemented, serum-free medium. Acinar cell exposure in vitro to dihydrotestosterone (DHT) resulted in a significant increase in cellular SC output. This hormone action was dose dependent and androgen specific. Testosterone, but not 17 beta-estradiol, progesterone, dexamethasone, or aldosterone, also induced a considerable elevation in acinar cell SC production. The effect of testosterone may not require intracellular enzymatic conversion to DHT. The impact of androgens on SC output was associated with enhanced cellular synthesis and secretion and did not involve variations in acinar cell viability or density. Moreover, the SC response to DHT occurred irrespective of whether lacrimal gland acinar cells were obtained from young adult male or female rats. In contrast, the androgen-related rise in SC production was significantly reduced in acinar cells isolated from tissue of orchiectomized and hypophysectomized rats. In summary, these findings demonstrate that androgens directly increase the synthesis of SC by lacrimal gland acinar cells in vitro. This effect, however, may be significantly altered by prior changes in the endocrine environment of acinar cells in vivo.

Aldosterone↗

PubMed1990

Characterization of an IgA receptor from group B streptococci: specificity for serum IgA.

Some strains of group B streptococci express a cell surface protein which binds IgA. This report describes some properties of such an IgA receptor and compares it with a previously described IgA receptor from group A streptococci. The group B receptor was released in an almost pure form from bacteria incubated at elevated pH, and could be isolated by IgA-Sepharose affinity chromatography. The sequence of the N-terminal 19 amino acid residues was unique. The receptor preferentially binds IgA of human origin, as shown in immunoblotting experiments with purified IgA from nine different species. The affinity constant of the purified receptor for serum IgA was determined to be 3.5 x 10(8) M-1, but for secretory IgA it was too low to allow determination. This result indicates that secretory component and/or J chain interferes with the binding of IgA to this type of bacterial receptor, which may be one of the physiological functions of these polypeptides. A reduction in affinity was also observed for another complexed form of IgA, alpha 1-microglobulin-IgA. The group B receptor is antigenically unrelated to the IgA receptor from group A streptococci (protein Arp), but competitive inhibition experiments indicate that they bind to the same region in IgA. The implications of these findings, and the biological role of bacterial IgA receptors, are discussed.

Amino Acid Sequence↗

PubMed1990

Stimulation of secretory IgA and secretory component of immunoglobulins in small intestine of rats treated with Saccharomyces boulardii.

Saccharomyces boulardii (S.b.) is largely used in Western European countries for the treatment of acute infectious enteritis and antibiotic-induced gastrointestinal disorders. To study the mechanisms of the protective effect of S.b. against enteral pathogen infection, we assessed the response of the intestinal secretion of secretory IgA (s-IgA) and of the secretory component of immunoglobulins (SC) to oral administration of high doses (0.5 mg/g body weight, three times per day) of S.b. cells in growing rats. S.b. cells (biological activity: 2.8 x 10(9) viable cells/100 mg) were administered daily by gastric intubation to weanling rats from day 14 until day 22 postpartum. Control groups received either 0.9% saline or ovalbumin following the same schedule. Expressed per milligram of cell protein, SC content was significantly increased in crypt cells isolated from the jejunum (48.5% vs saline controls, P less than 0.05) as it was in the duodenal fluid (62.8% vs saline controls, P less than 0.01) of rats treated with S.b. Oral treatment with S.b. had no effect on the secretion of SC by the liver. In the duodenal fluid of rats treated with S.b. cells, the mean concentration of s-IgA was increased by 56.9% (P less than 0.01) over the concentration of s-IgA measured in saline controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Rat polymeric IgA binds C1q, but does not activate C1.

Immune complexes, prepared with monoclonal rat IgA antibodies directed against DNP, activate the alternative pathway of the complement system in rat serum. In this study, the interaction of these monoclonal IgA antibodies with the classical pathway of complement was investigated. Monoclonal polymeric IgA (p-IgA) was shown to inhibit the IgG2b-mediated classical pathway-dependent lysis of TNP-coated sheep red blood cells. In addition, the binding of C3 to solid phase IgG2b immune complexes was inhibited by p-IgA. Monoclonal monomeric IgA (m-IgA) was much less efficient in this respect. To further analyse the effect of p-IgA on the activation of the classical pathway by IgG2b immune complexes, the interaction of p-IgA with C1 was studied. It was found that p-IgA antibodies bind C1q. No species-specificity was observed, since both rat and human C1q were bound. Whereas binding of C1q in C1 to IgG2b resulted in activation of C1, binding to p-IgA did not. The binding of C1q to both p-IgA and IgG2b could be inhibited by monoclonal antibodies directed against the globular heads of C1q, but not by monoclonal antibodies directed against the collagen tail. The formation of insoluble p-IgA immune complexes was inhibited in the presence of rat serum or C1. These studies indicate that C1q binds to p-IgA by its globular heads, and thereby may modulate classical pathway-mediated reactions such as the inhibition of immune precipitate formation.

Animals↗

PubMed1990

Immunological study of histologically non-involved jejunum during Crohn's disease: evidence for reduced in vivo secretion of secretory IgA.

We studied the local humoral immunity of histologically non-involved jejunum in patients with Crohn's disease. Normal subjects and patients with ulcerative colitis served as controls. Jejunal fluid samples were collected during segmental jejunal perfusion, under an occluding balloon and the in vivo jejunal secretion of the following proteins was determined: albumin, orosomucoid, transferrin, alpha 2-macroglobulin, secretory component, monomeric and polymeric IgA, IgG, and IgM. The densities and number of IgA-, IgG-, and IgM-containing cells in the lamina propria of the jejunum were measured on perendoscopic biopsies. Jejunal secretion of polymeric IgA and the density of IgA-containing plasma cells in the lamina propria were significantly lower in patients with Crohn's disease than in both control groups. This abnormal intestinal immune response, which was not correlated to the activity of the disease, might be involved in its pathogenesis.

Adolescent↗

PubMed1990

Oral immunization of mice with a live recombinant Yersinia enterocolitica O:9 strain that produces the cholera toxin B subunit.

The 70-kilobase pYV plasmid of Yersinia enterocolitica encodes a set of proteins called Yops that are produced during infection. To use Y. enterocolitica as a live carrier to present the cholera toxin B (CT-B) subunit to the immune system, we constructed an operon fusion between ctxB and the yop51 gene. This operon fusion was either cloned on an RSF1010-derived plasmid or integrated into the pYV plasmid itself. In Y. enterocolitica, both constructions directed the synthesis of free CT-B only under conditions of Yops production, i.e., at 37 degrees C in a medium deprived of Ca2+. Bacteria containing both types of recombinant plasmids were given orally to mice. A serum antibody response against CT-B was detected in both cases. A secretory immunoglobulin A activity specific to CT-B was also observed in the intestinal secretions. According to immunoblot analysis, the serum antibody response was only directed against the polymeric form of the B subunit. The ctxB gene was also inserted in frame within yop51, giving a chimeric Yop51-CT-B protein that was secreted into the surrounding medium. In this case, however, no antibody response was observed after oral inoculation of mice. This lack of response probably results from the inability of the hybrid protein to assemble into the polymeric form of the B subunit.

Animals↗

PubMed1990

Jejunal immunoglobulin and antigliadin antibody secretion in adult coeliac disease.

We compared the local intestinal immunoglobulin (Ig) secretion in six adult patients with coeliac disease and nine control subjects by perfusion of a small bowel segment under an occluding balloon and analysis of the perfusion fluid for the content of Ig and secretory component. The results were compared to the number of Ig-containing plasma cells in the test segment. There was, respectively, a two-fold and a fivefold increase in jejunal secretion rates of IgA (both monomeric and polymeric) and IgM in patients with coeliac disease compared with control subjects. The high IgA and IgM secretion rates parallel the increase of Ig-containing plasma cells in the lamina propria. In contrast, the IgG plasma cell density increase was barely significant in patients with coeliac disease and did not result in a high IgG secretion rate. The jejunal secretion rate of secretory component was significantly increased in patients with coeliac disease and no free dimeric IgA was present in the jejunal fluid. Antigliadin-IgA was detected in the serum and jejunal fluid of the six patients with coeliac disease. Antigliadin-IgA, however, was almost entirely polymeric IgA linked to secretory component in jejunal fluid, whereas 61% was dimeric IgA not linked to secretory component in serum. This result, combined with a raised secretory component secretion rate with no evidence of secretory component saturation, suggests that serum and intestinal antigliadin IgA might be of different origins in coeliac disease.

Adolescent↗

PubMed1990

Use of anti-cholera toxin IgA-secreting hybridoma cells for the elaboration of an antigen-specific IgA-ELISPOT-assay.

Hybridoma anti-cholera toxin (CT) IgA-secreting cells, because of their monoclonal character, were used to establish and optimize an ELISPOT-assay for CT-specific IgA-secreting cells. The use of hybridoma cells easily and quickly allowed the elaboration of a sensitive, specific and reproducible ELISPOT-assay, which was successfully applied to enumerate intestinal lamina propria lymphoid cells secreting anti-CT IgA in mice immunized twice intraintestinally with CT. Monoclonal antibody-secreting hybridoma cells, if available against a given antigen, are suggested as ideal cell suspensions to elaborate new ELISPOT-assays to study antibody responses at the cellular level.

Animals↗

PubMed1989

Neutralization of cholera toxin by rat IgA secretory antibodies induced by a free synthetic peptide.

Secretory immunoglobulin A (sIgA) is the major immunoglobulin in the bile of several species. They contribute to local immune defences of the gut. The protection against cholera toxin (CT) is due to the presence of specific sIgA in the bile and in the gut. We have already reported that oral administration of the peptide corresponding to the sequence 50-75 of cholera toxin B subunit elicits serum antibodies neutralizing CT activity, and that IgA and local protection are observed in the intestine of P50-75 orally immunized mice. In this study, we demonstrate the potential of this synthetic peptide as immunogen without carrier or adjuvant, not only in a strain known to be sensitive to CT, but also in an outbred one. Furthermore, this peptide stimulates the mucosal immunity, since we show that P50-75 induced-sIgA purified from rats bile and serum, are capable of neutralizing CT activity in the in vivo intestinal ligated loop test.

Animals↗

PubMed1989

Receptor binding-like specificity of two anti-cholera toxin monoclonal antibodies detected by latex agglutination immunoassay.

Six mouse monoclonal IgG antibodies (mAbs) reacting with the cholera toxin B-subunit (CT-B) were obtained from the spleen cells of mice immunized with CT. They were divided into two groups according to their different reactivities with CT in latex (Lx) agglutination. One group of two mAbs was called "non-repetitive" (NR) because they apparently recognized a single epitope on CT, which was unable to agglutinate Lx coated with these NRmAbs, in contrast with the other group of four mAbs that we called "repetitive" (RmAbs). The two NRmAbs, but not the four RmAbs, failed to react with CT when CT was bound first to its GM1-receptor. Thus, the NRmAbs seemed directed at an epitope close to the GM1-binding site of CT-B. These NRmAbs could represent valuable immunogenic candidates for anti-idiotypic immunization against CT and related enterotoxins.

Animals↗

PubMed1989

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↗

PubMed1989

Surface IgA and Fc-alpha receptors on human alveolar macrophages from normal subjects and from patients with sarcoidosis.

Human alveolar macrophages (AM) obtained by bronchoalveolar lavage (BAL) were found to bear cytophilic IgA and Fc alpha-receptors (Fc alpha R) on their surface. The cytophilic IgA belongs to the IgA1 subclass, but unoccupied receptors can be saturated with either IgA1 or IgA2 molecules. Although both polymeric and monomeric forms could attach, binding was about 5-fold greater for the polymers. Both cytophilic IgA and Fc alpha R are sensitive to trypsin and disappear after 18 h of AM culture. An increase in cytophilic IgA was observed on AM from untreated patients with pulmonary sarcoidosis, but not on AM from steroid-treated patients. A significant correlation was found between IgA levels in BAL and the percentage of AM with cytophilic IgA in normal subjects and in steroid-treated sarcoid patients. However, no such relationship was seen among untreated patients. These data suggest that multiple factors may modulate AM surface receptors for IgA. Inflammatory events occurring in the lungs could alter receptor expression and perhaps be of significance in the immunophysiopathology of certain pulmonary diseases.

Binding, Competitive↗