Extended cryopreservation of Loa loa and Mansonella perstans microfilariae from human peripheral blood.
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Blood↗
Biomedical subjects
A Capron
Publications and source records attributed to A Capron.
Identification and isolation of Trypanosoma cruzi trypomastigote cell surface protein with properties expected of a fibronectin receptor.
The fibronectin receptor of Trypanosoma cruzi trypomastigotes was identified using immunoprecipitation procedure. Parasite radioiodinated surface material was incubated with fibronectin followed by rabbit IgG anti-fibronectin and protein A-Sepharose. The precipitates were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Two radioactive bands were seen. One of 220 kDa corresponded to a subunit of fibronectin molecule present on the parasite surface at the time of isolation. The major radioactive band of 85 kDa corresponded to the fibronectin receptor. Fibronectin receptor was purified using affinity chromatography on human fibronectin coupled to Sepharose. Analysis of fibronectin receptor by sodium dodecyl sulfate-polyacrylamide gels demonstrated one major band of 85 kDa. The purified fibronectin receptor was active since 40-60% of labeled receptor could rebind to fibronectin-Sepharose. In addition, fibronectin receptor could interact with cells bearing fibronectin molecules as shown by the binding of 125I-labeled fibronectin receptor to human monocytes and neutrophils as well as cloned 3T3 fibroblasts. The binding could be inhibited by treatment of cells with anti-fibronectin antibodies. Finally, we showed that the affinity-purified fibronectin receptor and antibodies to the receptor exerted an inhibitory effect on the infection of 3T3 fibroblasts by T. cruzi trypomastigotes in an in vitro culture system.
Animals↗
Stimulation of Schistosoma mansoni miracidia by a 80 kDa glycoprotein from Biomphalaria glabrata.
Soluble extracts of Biomphalaria glabrata stimulate in vitro incorporation of methionine in Schistosoma mansoni miracidia. Evidence is presented that a unique 80 kDa glycoprotein representing less than 0.01% of total snail proteins and uniformly distributed in the snail body, is responsible for the observed stimulation. This protein specifically acts on the miracidia and this observation suggests that this glycoprotein influences snail penetration and development of miracidia. However, the presence of molecules stimulating S. mansoni miracidia was also demonstrated in S. mansoni nonpermissive molluscs.
Animals↗
Rats, mice and men - models for immune effector mechanisms against schistosomiasis.
Experimental studies have demonstrated the diversity of immune effector mechanisms against schistosomes. Among the various animal models, the rat appears as an excellent experimental system for investigation of antibody-mediated immunity to Schistosoma mansoni. Rat monoclonal antibodies have allowed the identification of effector and regulatory mechanisms operating in human infection, together with the characterization of protective antigens, leading to promising approaches to vaccine development.
Journal Article↗
A role for glycoprotein IIb-IIIa complex in the binding of IgE to human platelets and platelet IgE-dependent cytotoxic functions.
A possible relationship between binding sites for Immunoglobulin E (IgE) on human platelets, involved in IgE-dependent cytotoxic functions of platelets against helminth parasites, and well-characterized platelet constituents involved in haemostasis, was investigated. We first explored the interaction with IgE of platelets from patients with rare inherited deficiencies of defined platelet constituents and functions: Glanzmann's thrombasthenia, Bernard-Soulier and grey platelet syndromes. We report that only type I and II thrombasthenic platelets, which lack the membrane glycoproteins (GP) IIb and IIIa, failed to bind IgE and to exhibit IgE-dependent effector functions. Since thrombasthenic monocytes, however, showed normal interaction with IgE, this defect appeared restricted to platelets. Polyclonal and monoclonal antibodies directed against GP IIb-IIIa complex, but not monoclonal antibody directed against GP Ib, inhibited the binding of IgE to normal platelets, and their IgE-dependent cytotoxicity. Taken together, these findings indicate a relation between the GP IIb-IIIa complex and the expression of IgE binding sites and IgE-dependent effector functions in human platelets.
Blood Platelets↗
The immunodominant epitope of the major membrane tachyzoite protein (P30) of Toxoplasma gondii.
Several physicochemical characteristics of the repeated epitope of the major surface protein (P30) of Toxoplasma gondii were investigated with an anti-P30 mAb by two different methods: a one-site/inhibition assay that detects molecules containing single or multiple epitopes and a two-site/one antibody radiometric assay that is only effective with antigenic molecules containing two or more identical epitopes. Using both techniques, the repeated epitope within purified P30 was stable after 1 h at 63 degrees C, but labile at 100 degrees C. It was also resistant to successive freezing and thawing, and not affected after one year at -70 degrees C. Lyophilization and acidic or basic treatment had no effect. This epitope was also resistant to 20% trichloroacetic acid precipitation (activity recovered in the pellet) and to precipitation with cold acetone. To investigate the immunodominance of this repeated epitope during the humoral immune response against T. gondii, competition binding assays between anti-P30 mAb and polyclonal antibodies, from rabbits immunized with either purified P30 or total Toxoplasma extract and from patients with toxoplasmosis, have been used. We found that the mAb inhibited 50-95% of the binding of the IgG antibodies from both rabbits to purified P30. In addition, the binding of both human IgG and IgM antibodies to P30 was significantly inhibited by the mAb. It appears, therefore, that a single region of P30 contains most of the immunogenic activity.
Animals↗
Role of serine proteases of Schistosoma mansoni in the regulation of IgE synthesis.
The regulation of the IgE response by schistosomula-released products (SRP) was studied either in vitro with rat and human cell cultures or in vivo by injection into rats of SRP with an unrelated allergen at primary or secondary immunization. The results obtained in vitro showed that non-dialysable factors present in SRP potentiate the IgE synthesis by rat and human cells. This enhancing effect was supported by molecules with serine protease activities. On the other hand, the inhibition or depletion of SRP in serine proteases induced a weak synthesis of IgM by rat cells in vitro. The injection of SRP into rats on day 0 with an unrelated allergen led to a potentiation of total IgE production, but an inhibition of specific IgE response. In contrast, a marked elevation of specific IgE response was obtained when SRP was injected upon secondary immunization. Serine proteases of SRP were partly responsible for this potentiative effect.
Animals↗
Antischistosomal effect of cyclosporin A: cure and prevention of mouse and rat schistosomiasis mansoni.
C57BL/6 mice infected with Schistosoma mansoni at day 0 and injected with cyclosporin A (CyA) either daily or from day -1 to day 3 were protected against schistosomiasis mansoni as indicated by a decrease in the number of worms recovered from the liver 45 days after infection. CyA treatment also protected rats and strains of mice with known immunity defects (nu/nu, P/N, CBA/N). Protection was evident against both primary and secondary infection in mice infected at day 0, reinfected at day 42, and treated daily with CyA either during the course of the experiment or only from day -1 to day 3, as indicated by the worm burden at day 67. In such an experiment of infection and reinfection, the immature worms were shown to be the target of CyA. Administration of the drug 27, 45, 62, or 100 days before infection confirmed the long-term protective effect of CyA. This drug did not evoke the killing of adult worms in vivo. These data confirm and define the curative and preventive effect of CyA against schistosomiasis mansoni.
Animals↗
Induction of a protective immune IgE response in rats by injection of defined antigens of schistosomulum-released products: immunochemical properties of the target antigens.
Brown Norway rats were injected without adjuvant with the soluble products liberated in a 16-hour culture by schistosomula (schistosomula-released products, SRP-A). A strong cytotoxic and protective IgE response was elicited, mainly directed against 22- and 26-kilodalton (kDa) SRP-A molecules. In the present study, we have attempted to characterize further those molecules. Metaperiodate denaturing treatment of the SRP-A glycans before injection into rats did not modify the immunogenicity of the SRP-A antigens. Results obtained by lectin affinity suggested that the 22- and 26-kDa molecules were glycoconjugates binding to ConA. Preparative sodium dodecylsulfate electrophoresis has allowed the separation of enriched fractions of 22- and 26-kDa molecules which have been injected separately into rats. The corresponding sera were tested in antibody-dependent cell cytotoxicity and displayed a significant cytotoxic IgE response (65 and 53%, respectively) towards the larvae. These results lend further support to the view that the 22- and 26-kDa antigens are the major targets of the protective IgE response and thus appear as potentially protective antigens.
Animals↗
Measurement of picogram quantities of rat IgE from in vitro culture supernatants of B lymphocytes in experimental helminth infections.
A double-antibody liquid-phase radioimmunoassay was used to measure picogram quantities of rat IgE. The sensitivity of this method (approximately 10 pg/ml) allowed the determination of the production of IgE in in vitro culture supernatants of B lymphocytes of infected animals.
Animals↗
Schistosome-derived inhibitory factor: an immunosuppressive agent preferentially active on T lymphocytes.
We have previously shown that schistosome-derived inhibitory factors (SDIF) inhibited lymphocyte proliferation and induced immunosuppression. Crude SDIF was purified by successive gel filtration and reverse-phase high-performance liquid chromatography. Purified SDIF preparations strongly inhibited the proliferation of different T cell line cells, while other cell lines (B cells, macrophages and fibroblasts) were almost not affected by SDIF. The inhibition of T cell proliferation by SDIF was not mediated through an Interleukin-2-dependent mechanism since both Interleukin-2-dependent and -independent T cells were inhibited. SDIF-activity was absorbed by cells in a time- and cell-number-dependent fashion at 4 degrees C, suggesting the existence of a possible receptor for SDIF. However, the difference in sensitivity to SDIF proliferation inhibition could not be attributed to the presence or absence of this receptor since cells from SDIF-sensitive and SDIF-resistant cell lines absorbed SDIF activity in the same way.
Absorption↗
Development of a competitive radioimmunoassay for human plasma fibronectin.
A competitive radioimmunoassay (CRIA) for quantitating human plasma fibronectin levels has been developed and compared with a conventional immunoturbidimetry assay (IMTA). The assay ranges for CRIA and IMTA were 0.05-5 micrograms/ml and 100-1,000 micrograms/ml, respectively, and the lowest detectable amounts of fibronectin that differed significantly from zero were 17.6 ng and 50 micrograms. The correlation coefficient between CRIA and IMTA was r = 0.953 (p less than 0.001). We consider the CRIA as potentially useful in the identification and study of fibronectin in certain biological fluids where it may be present in low concentrations.
Blood Specimen Collection↗
Raised serum IgG4 levels in patients with atopy and filariasis: application of an automated particle-counting immunoassay using monoclonal antibody.
We show here an automated (50 samples/h) assay for serum IgG4 having a throughput time of 40 min per sample and a sensitivity of 10 micrograms/ml. The assay procedure is based on the inhibition by sample of the agglutination reaction between monoclonal anti-IgG4 antibodies and latex particles to which IgG4 myeloma protein has been coupled. Assay reliability was ascertained by testing for linearity, analytical recovery (96.4%), interassay precision (less than or equal to 8%), specificity and correlation between the results obtained with monoclonal and polyclonal anti-IgG4 antibodies (n = 84; rs = 0.97). Application of the assay to sera from various groups of patients indicated significantly (p less than 0.00005) higher geometrical means (Gx) in patients suffering from atopy (n = 87; Gx = 617 micrograms/ml), atopic dermatitis (n = 28; Gx = 1,043 micrograms/ml), filariasis with Onchocerca volvulus (n = 48; Gx = 1,681 micrograms/ml) and Brugia malayi (n = 20; Gx = 1,078 micrograms/ml) as compared to nonatopic subjects (n = 103; Gx = 302 micrograms/ml) and randomized paired maternal/cord sera (n = 41; Gx = 276 and 296 micrograms/ml, respectively). IgG4 in the paired maternal/cord sera correlated (r = 0.98; p less than 0.00005). There was no significant influence of age or sex on the IgG4 levels either among the nonatopics or the atopics even though low IgG4 (less than or equal to 30 micrograms/ml) was more common among women. The results suggest that IgG4 and IgE responses are somehow closely related in atopic and parasite-infested patients at the physiological, pathogenic or genetic level.
Adolescent↗
Alveolar macrophage and its participation in the inflammatory processes of allergic asthma.
Purified alveolar macrophages (AM) obtained by bronchoalveolar lavage of allergic asthmatic patients are stimulated by incubation with anti IgE or the exposure to the related allergen. Confirming the demonstration of a receptor for the Fc fragment of IgE on the surface of macrophages, IgE was characterised on AMs by a rosette-assay, showing an increased percentage of cells forming rosettes with red blood cells coated with anti-IgE or the specific allergen. The IgE-dependent secretion of arachidonic acid metabolites, PAF-acether and chemotactic factors for neutrophils and eosinophils demonstrated in vitro, together with the in vivo demonstration of the activation of AMs by a local provocation test, suggest that besides mast cell, AM do participate in the inflammatory processes of allergic asthma.
Antibodies↗
Nedocromil sodium inhibits IgE-dependent activation of rat macrophages and platelets as measured by schistosome killing, chemiluminescence and enzyme release.
The IgE-dependent activation of peritoneal macrophages and blood platelets can be measured by anti-parasite cytotoxicity, chemiluminescence and, in macrophages, lysosomal enzyme activity. Using these parameters, the present study demonstrates an inhibition by nedocromil sodium of the IgE-mediated stimulation of these non-mast cell inflammatory populations in the rat. These observations suggest that nedocromil sodium may be of value in the treatment of diseases of the lung where inflammatory mediator release is implicated.
Animals↗
[Hypocomplementary membrano-proliferative glomerulonephritis in a Malagasy patient with schistosomiasis mansoni (detection of bilharzial antigen on glomerular basement membrane using monoclonal antibodies)].
Schistosomiasis due to Schistosoma mansoni affects more than 40 millions people all over the world. Renal involvement is observed mainly in endemic areas. We report a case of hypocomplementemic membrano-proliferative glomerulonephritis in a malagasy man who suffered also from hepatosplenic bilharziosis. The relation between Schistosoma mansoni and the nephropathy was proved by indirect immunofluorescence test using a monoclonal antibody directed against the caecum of adult Schistosoma mansoni.
Adult↗
Detection and quantification of circulating antigen in schistosomiasis by a monoclonal antibody. I. Specificity analysis of a monoclonal antibody with immunodiagnostic capacity.
Monoclonal antibodies were obtained after immunization of mice with Schistosoma mansoni excretory/secretory antigen, previously shown to contain the circulating cathodic (M) antigen. Among these, the 40:B1 monoclonal antibody proved to be specific for the schistosome genus and to detect only adult worm-derived antigens as shown both by immunoprecipitation and with a two-site immunoradiometric assay using the monoclonal as both the solid-phase and the labelled antibody. The two-site immunoradiometric assay allows a sensitive measurement (detection limit: 5 ng) of circulating schistosome antigen in blood and in urine from patients with schistosomiasis. The amount of circulating schistosome M antigen is correlated with schistosome egg excretion in stool.
Animals↗
Detection and quantification of circulating antigen in schistosomiasis by monoclonal antibody. II. The quantification of circulating antigens in human schistosomiasis mansoni and haematobium: relationship to intensity of infection and disease status.
Circulating cathodic and circulating anodic antigens were quantified in sera of patients infected with S. mansoni, S. haematobium or both parasites. A monoclonal antibody and a polyclonal antiserum were applied in precipitation and solid phase immunosorbent techniques using radio- and enzyme-labelled antibody as a tracer to detect the cathodic and anodic antigen respectively. The results show that circulating cathodic antigen can frequently be detected in an immunoprecipitation or an immunoradiometric assay in serum of infected patients. The serum concentration of this antigen was found to be significantly correlated to the number of S. mansoni worms and to be higher in patients with the hepatosplenic form of the disease than in those without such complications. Examining paired serum samples before and after specific treatment the determination of this antigen by monoclonal antibody reliably indicated efficacy of chemotherapy in patients having received different forms of treatment.
Adolescent↗