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J Ivanyi

Publications and source records attributed to J Ivanyi.

At least 145 records · Page 8Linked to original sources
PubMed1986

Immunological activity of a 38-kilodalton protein purified from Mycobacterium tuberculosis.

A 38-kilodalton (kDa) protein antigen from Mycobacterium tuberculosis was purified by monoclonal antibody TB71-based affinity chromatography. This molecule carries two nonoverlapping epitopes recognized by monoclonal antibodies TB71 and TB72, which are expressed substantially more strongly by M. tuberculosis than by Mycobacterium bovis. However, cross-reactive determinants between these two species were revealed on the 38-kDa protein by a rabbit anti-BCG serum. An immunoradiometric assay based on the TB71 and TB72 antibody pair specifically determined 38-kDa-antigen concentrations in mycobacterial extracts. Antibodies in sera from tuberculosis patients estimated by binding to 38-kDa-antigen-coated microtiter plates were positively correlated with TB72 competing titers. Unlike antibodies, T-cell proliferative responses to the 38-kDa protein were expressed equally by 60% of tuberculosis patients and healthy BCG-vaccinated subjects. Similarly, delayed-type hypersensitivity skin reactions were elicited in both M. tuberculosis- and M. bovis-sensitized guinea pigs. The results suggest the immunodominance of the species-specific B-cell and cross-reactive T-cell stimulatory epitopes.

Animals↗
PubMed1986

Potentiation of the somatogenic and lactogenic activity of human growth hormone with monoclonal antibodies.

Monoclonal antibodies of certain epitope specificity have been shown to produce a marked dose-dependent enhancement of the somatogenic and lactogenic activity of human GH (hGH). Two antibodies (EB1 and EB2), binding to distinct antigenic determinants and expressed on both hGH and human chorionic somato-mammotrophin (hCS), significantly enhanced the hGH-stimulated uptake of 35S-labelled sulphate into cartilage. Similarly, these antibodies enhanced the lactogenic activity of both hGH and hCS in the pigeon crop sac test. Two hGH specific monoclonal antibodies (QA68 and NA71), defining a further two epitopes, exhibited only modest enhancing or inhibitory activity in these assays, whereas the binding of certain combinations of monoclonal antibodies resulted in either reversal of enhancement or inhibition of hormone activity. Univalent antibody fragments derived from EB1 were as enhancing as the intact antibody indicating that bivalency dependent mechanisms were not involved in the phenomenon. Enhancing monoclonal antibodies were relatively poor inhibitors of 125I-labelled hGH binding to liver microsomal receptors, which is in contrast with their previously described property of potent suppression of hGH interaction with lymphoid cell receptors. It is tentatively concluded that 'restriction' of hormone binding to particular hGH receptors, relevant to somatic growth or lactogenic activity, may play a role in the enhancement phenomenon of hGH in vivo.

Animals↗
PubMed1986

Control by H-2 genes of murine antibody responses to protein antigens of Mycobacterium tuberculosis.

The genetic control of antibody responses after immunization with Mycobacterium tuberculosis soluble antigens was examined in inbred and H-2 congenic mouse strains. Antibody levels to five distinct epitopes were determined by a competitive inhibition test using radiolabelled murine monoclonal probes. High or low responder antibody levels were associated with either the H-2b (TB23, TB71 and TB72 specificities) or the H-2k (TB68) allele on both B10 and BALB backgrounds. The high response of TB78 specificity associated with the H-2k on the BALB but with H-2b haplotype on B10 background. The phenotype of (C57BL/6 X CBA)F1 hybrids reflected the high response for four and the low or intermediary response for one (TB68) of the tested paratopes. This is the first demonstration of immune response gene control in respect of defined mycobacterial protein epitopes. The implications towards the analysis of pathogenic or protective mechanisms during mycobacterial infection are briefly outlined.

Animals↗
PubMed1985

Detection of an antigen (MY4) common to M. tuberculosis and M. leprae by 'tandem' immunoassay.

A novel 'tandem' immunoassay for the detection of mycobacterial antigen was devised using a monoclonal antibody (ML 34) both as solid phase 'capture' and as the 125I- or enzyme-labelled 'tracer' antibody. This antibody binds to the repeating epitopes (MY4b) of a water-soluble protease-resistant antigen from M. tuberculosis, M. leprae and some other species of mycobacteria. Optimal binding results could be obtained within 4 h by the consecutive incubation of ML34-coated microtitre plates with antigen followed by the labelled ML34 antibody. The binding of intact bacilli was positive for M. tuberculosis but not for M. leprae. These results suggested that the MY4 antigen is expressed on the surface of M. tuberculosis and internally within M. leprae. Analysis of subcellular fractions suggested that this antigen is a constituent of cell walls.

Animals↗
PubMed1985

Topographic and functional assay of antigenic determinants of human prolactin with monoclonal antibodies.

Six distinct antigenic determinants were identified on human prolactin (hPRL) by competition assays with murine monoclonal antibodies (MABs). The affinity of binding and the cross-reactivity of the antibodies with two non-primate prolactins was also determined. Binding of 125I-hPRL to MAB-coated microtitre plates in the presence of a second MAB resulted in either inhibition or enhancement of antigen binding to the plate. These results were interpreted in terms of conformational changes to epitopes, induced allosterically by the binding of a second MAB to the antigen. The topographic relationship of epitopes to the biologically active regions on the hormone was examined on the basis of the neutralizing potency of MABs in the proliferation of the prolactin-dependent cell line NB2. The NB2 growth-inhibitory activity was restricted to three distinct epitopes (NE02/6, 1208 and NE03) but absent from three other MABs tested (QB01, WC01/3 and 1200). On the basis of the competition and functional studies, an elemental scheme of the topographic localization of epitopes is presented. The experimental approach employed may contribute to studies on the allocation of biologically active sites on protein hormones.

Animals↗
PubMed1985

Monoclonal antibodies to human growth hormone can distinguish between pituitary and genetically engineered forms.

Monoclonal antibodies (MABs) prepared against human pituitary growth hormone (hGH) have been compared for their binding to pituitary-derived and genetically engineered methionyl growth hormone (met-hGH). The antibodies bind to four non-overlapping epitopes of which two are completely shared with human choronic somatomammotropin (hCS). The determinant defined by MAB NA27 was expressed on met-hGH to a lesser degree than on hGH of pituitary origin. However, another antibody, QA68, which binds to a determinant closely related to NA27, failed to discriminate between hGH and met-hGH. A further two MABs (EB1 and NA71) were similarly ineffective in distinguishing between the two forms of the hormone. The determinant recognized by antibody EB2 was equally represented on hGH and met-hGH when assessed by a liquid-phase radioimmunoassay: however, measurement of the binding in a solid-phase assay resulted in a two-four-fold lower binding to met-hGH. Bioactivity assessed by both an in vitro cell proliferation assay and an in vivo cartilage sulphation bioassay failed to distinguish between the two hormones. It is therefore concluded that the NH2-terminal methionine on bacterially derived growth hormone results in altered antigenicity of the hormone without any measurable effect on bioactivity.

Animals↗
PubMed1985

The effects of prostaglandin E and I analogues on lymphocyte stimulation.

The prostacyclin analogue carbacyclin and the prostaglandin E analogues hydantoin no. 245C77 and no. 454C77 were potent inhibitors of mitogen-stimulated DNA and protein synthesis by cultured pig peripheral blood lymphocytes with ID50 concentrations between 10(-5) and 10(-8)M. These effects were comparable to those of PGE2. Strong inhibition was observed only with carbacyclin when human lymphocyte cultures were used. These results show that stable prostaglandin analogues may exhibit at least some of the activities of the naturally occurring PGE2 in this system, and support the concept that prostacyclins may also play a role in regulating immunological responses.

Dinoprostone↗
PubMed1985

Dissection of Mycobacterium tuberculosis antigens using recombinant DNA.

A recombinant DNA strategy has been used systematically to survey the Mycobacterium tuberculosis genome for sequences that encode specific antigens detected by monoclonal antibodies. M. tuberculosis genomic DNA fragments with randomly generated endpoints were used to construct a large lambda gt11 recombinant DNA expression library. Sufficient numbers of recombinants were produced to contain inserts whose endpoints occur at nearly every base pair in the pathogen genome. Protein antigens specified by linear segments of pathogen DNA and produced by the recombinant phage of Escherichia coli were screened with monoclonal antibody probes. This approach was coupled with an improved detection method for gene isolation using antibodies to clonally isolate DNA sequences that specify polypeptide components of M. tuberculosis. The methodology described here, which is applicable to other pathogens, offers possibilities for the development of more sensitive and specific immunodiagnostic and seroepidemiological tests for tuberculosis and, ultimately, for the development of more effective vaccines.

Antibodies, Monoclonal↗
PubMed1985

Immunoassays of field isolates of Mycobacterium bovis and other mycobacteria by use of monoclonal antibodies.

Antigen extracts obtained by sonication of 22 strains of Mycobacterium bovis from cattle and badgers together with extracts of strains of M. tuberculosis, M. paratuberculosis, M. avium, M. africanum, M. kansasi, M. leprae and BCG were examined with a panel of 10 monoclonal antibodies to M. tuberculosis or M. leprae. Antigen extracts were coated in aqueous solution (wet coating) and the extracts were also dried on to the polyvinyl plates (dry coating). When dry coating was compared to wet coating, there was a major increase in the binding of monoclonal antibody ML03 to M. avium and M. paratuberculosis, monoclonal antibody ML02 to M. paratuberculosis, and monoclonal antibodies TB71 and TB72 to the majority of M. bovis isolates. The study confirmed that on wet-coated plates, monoclonal antibodies TB71 and TB72 bind poorly or not at all to M. bovis and that monoclonal antibodies TB68, TB78, TB77 and TB23 each bind to field strains of M. bovis while TB23 binds poorly to BCG in wet-coating conditions. Antibodies TB72 and TB71, originally thought to be specific for M. tuberculosis, each reacted with M. africanum. Antibody TB78 bound to M. paratuberculosis but did not react with M. avium, and M. avium and M. paratuberculosis were distinguished from M. bovis and M. tuberculosis by the binding of antibody ML03 to dry-coated plates. When wet-coated plates were used, ML03 bound strongly only to M. leprae. The panel of monoclonal antibodies did not demonstrate distinct serotype differences between the field isolates of M. bovis.

Animals↗
PubMed1985

Detection of mycobacterial antigen and antibodies in the cerebrospinal fluid of patients with tuberculous meningitis.

An immunodiagnostic test for the detection of a soluble nonprotein mycobacterial antigen by reverse passive haemagglutination with IgM murine monoclonal antibody was developed. The test was used to analyse the cerebrospinal fluid of 89 patients with tuberculous meningitis (TBM) from India and 127 control subjects from India and the UK. The antigen was demonstrable in 88% of culture-positive and 73% of culture-negative TBM patients. However, it was also detected in 21% of Indian patients with pyogenic meningitis, and in 8% of Indian and 1% of UK control subjects. Antibodies binding to a soluble mycobacterial extract were detected at low titre in 68% of all subjects with TBM and in 37% of Indian cases of pyogenic meningitis. Because patients with TBM had raised levels of the antigen and of antibodies to the antigen, the possible role of immune complexes in the pathogenesis of the disease is briefly discussed.

Antibodies, Bacterial↗
PubMed1985

Identification of a 68-kilodalton protective protein antigen from Bordetella bronchiseptica.

A 68-kilodalton (kd) outer membrane protein antigen of Bordetella bronchiseptica has been identified by using monoclonal antibodies that recognized two nonoverlapping determinants. Antibody BB05 also reacted with homologous proteins from Bordetella pertussis and Bordetella parapertussis but not with another 12 organisms from various bacterial genera. Passive injection of BB05 antibody protected mice from aerosol infection with B. bronchiseptica as shown by reduced mortality and reduced pathology of turbinate bones. The 68-kd B. bronchiseptica antigen was purified by BB05-based affinity chromatography and evaluated for its potency to immunize mice actively against either intraperitoneal or aerosol challenge with B. bronchiseptica. Immunization with the 68-kd antigen in incomplete Freund adjuvant significantly reduced the levels of mortality in intraperitoneally challenged mice. In the aerosol infection model, injection of the 68-kd antigen with complete or incomplete Freund adjuvant or saponin reduced the bacterial counts in the lungs of infected mice. These results suggest that the 68-kd protein may represent a potential "protective" antigen of B. bronchiseptica.

Animals↗
PubMed1985

Monoclonal antibody-mediated enhancement of growth hormone activity in vivo.

This work demonstrates that complexing hGH with monoclonal antibody EBl (MAB-EBl) can produce a striking potentiation of the somatogenic actions of hGH in vivo in Snell dwarf mice. In short-term experiments significant increases in cartilage metabolism and body weight were noted; these responses were dose-dependent for both MAB-EBl and hGH concentration. Increased growth was also observed in long-term experiments. In marmosets where MAB-EBl cross-reacts with endogenous GH, MAB-EBl alone enhanced the actions of endogenous GH. A new perspective may be necessary to incorporate these results into the current concept of antibody action.

Animals↗