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Biomedical subjects

J Ivanyi

Publications and source records attributed to J Ivanyi.

At least 163 records · Page 9Linked to original sources
PubMed1985

Serological survey of leprosy and control subjects by a monoclonal antibody-based immunoassay.

A serological antibody competition test (SACT) using a murine anti-Mycobacterium leprae-specific monoclonal antibody (ML04) has been evaluated in 96 untreated leprosy patients and 128 control subjects. The test is based on the competitive inhibition by antibodies from human test sera of the binding of the specific 125I-ML04 murine monoclonal antibody to M. leprae soluble antigen coated microtiter plates. Along the spectrum of the disease, SACT positivity was observed in 100% of LL-BL, 87.5% of BB, and 46.7% of the TT-BT groups of patients. Moreover, 46.4% of apparently healthy household family contacts of multibacillary leprosy cases were also antibody positive. Sera from 15 contacts of paucibacillary leprosy cases as well as from 85 various nonleprosy subjects (tuberculosis, autoimmune disease, cancer, and healthy) were all found to be negative. These results satisfy the requirements of a leprosy-specific serodiagnostic test. The striking increase of antibody titer in all of the LL/BL patients indicates a potential prognostic utility of this test for the lepromatous shift of the disease. The observed positivity in a fraction of healthy leprosy contacts still requires prospective evaluation of disease incidence in a larger test sample.

Antibodies, Bacterial↗
PubMed1984

Post-natal ontogenesis of graft-versus-host reactivity of peanut agglutinin lectin-negative thymocytes in the chicken.

Chicken thymocyte fractionation by peanut agglutinin lectin yields two cell subpopulations which differ in their GvH competence when injected into major histocompatibility complex (MHC)-(B locus) incompatible embryos. The nonagglutinated PNA- fraction displayed a degree of alloreactivity similar to that of peripheral blood lymphocytes while the PNA+ cells were nonreactive. Analysis of chickens at the age of 4 to 24 weeks showed that the development of GvH-reactive PBL preceded by 12 weeks the maturation of GvH-reactive PNA- thymocytes. Possible interpretations for this difference between the time of appearance of GvH reactivity of PNA- thymocytes and PBL are discussed.

Animals↗
PubMed1984

Characterization of monoclonal antibodies against beta-bungarotoxin and their use as structural probes for related phospholipase A2 enzymes and presynaptic phospholipase neurotoxins.

Hybridoma lines secreting monoclonal antibodies against a phospholipase-inactive derivative of the presynaptic neurotoxin, beta-bungarotoxin, have been established. These antibodies, either of the IgG1 or IgG2b isotype with affinities in the range 1-2 X 10(8) 1/mol, recognized a single immunodominant region of native beta-bungarotoxin, most probably located on the A (phospholipase homologue) chain of the toxin. Using plate-adsorbed radioimmunoassay procedures, antibodies reacted with native beta-bungarotoxin and other beta-bungarotoxin isotoxins as well as with the non-toxic phospholipase A also present in Bungarus multicinctus venom. Other phospholipase A enzymes and presynaptic phospholipase neurotoxins did not show any competition with beta-bungarotoxin in the radioimmunoassay. Globulin fractions of monoclonal antibodies partially inhibited the phospholipase activity of beta-bungarotoxin.

Animals↗
PubMed1984

Identification of Mr variants of prolactin with monoclonal antibodies.

Monoclonal antibodies ( QB01 and 1200) prepared against human prolactin (hPRL) have helped define a variant form of the hormone. This variant is of apparently higher molecular mass (26 kDa) than the predominant form of the hormone (24 kDa) and its presence does not appear to be species-restricted. The demonstration of the 26 kDa form of hPRL in fresh pituitary tissue and amniotic fluid suggests it may retain some specific function.

Amniotic Fluid↗
PubMed1984

The effects of indomethacin on T lymphocyte stimulation.

Immunomodulatory effects of indomethacin on mitogen-induced [3H]thymidine incorporation in cultured pig peripheral blood lymphocytes were demonstrated. In monocyte-containing lymphocyte cultures, indomethacin enhanced lymphocyte stimulation, whereas in monocyte-depleted cultures indomethacin inhibited the response. Indomethacin effects were most marked at suboptimal to optimal concentrations of mitogen and decreased at superoptimal concentrations in both types of culture. The effects of prostaglandin E2 at superoptimal mitogen concentrations were found paradoxically to be stimulatory. The results indicate that arachidonic acid metabolites may have both positive and negative effects on lymphocyte activation.

Animals↗
PubMed1983

Ontogenic restriction of colonization of the bursa of Fabricius.

The capacity of hemopoietic precursor cells (HPC) to home to embryonic bursal and thymic grafts was investigated in embryonic and newly hatched chickens. Whereas thymic grafts developed normal histogenesis in both types of recipients, the bursal rudiment was colonized and developed in embryonic, but not in newly hatched hosts. In the latter, noncolonized bursal grafts developed neither lymphoid follicles nor granulopoiesis in the mesenchyme. These results are interpreted in terms of ontogenic "maturation" of the HPC which lose their homing potential towards the bursa while they preserve their thymic seeding capacity. This hypothesis is consistent with previously reported data which indicated cyclic continuous recruitment of the thymic lymphoid population, but restricted bursal colonization to a relatively brief period of embryonic life.

Animals↗
PubMed1983

Antigenic, receptor-binding and mitogenic activity of proteolytic fragments of human growth hormone.

Analysis of the subtilisin-digested, two-chain form of human growth hormone (hGH) and its constituent polypeptide fragments has been aided by the use of monoclonal antibodies which bind specifically to four distinct epitopes on the native hormone. Using the SDS-polyacrylamide immunoblotting technique, it was shown that one epitope (shared with human chorionic somatomammotropin) detected by EB1 (or EB3) antibody was expressed to a similar extent by both the N-terminal (15 K) and C-terminal (7 K) polypeptides. This epitope is unique in that it represents a repeating determinant within the single chain structure of the hormone. Another three epitopes detected by monoclonal antibodies QA68/NA27, NA71 or NA39/EB2 were absent from the 7-K fragment but were expressed on the 15-K fragment to a similar extent to that on unmodified growth hormone. Binding of NA71 antibody was demonstrated only by radioimmunoassay since this, presumably conformational epitope could not be detected by immunoblotting. The functional importance of the 15-K peptide was demonstrated by its ability to bind specifically to hormone receptors on IM9 human lymphoblastoid cells and by its retention of mitogenicity for the NB2 rat lymphoma cell line. However, all tested monoclonal antibodies inhibited the binding of [125I]15-K to IM9 cell receptors by either steric hindrance or by an allosteric mechanism and therefore could not be further related topographically to the receptor-binding moiety of hGH.

Animals↗
PubMed1983

A serological test for leprosy based on competitive inhibition of monoclonal antibody binding to the MY2a determinant of Mycobacterium leprae.

A novel serological assay for leprosy has been devised on the basis of serum inhibition of binding of 125I-labelled ML04 monoclonal antibody to Mycobacterium leprae sonicate-coated microtitre plates. Antibodies were detected in 93% of lepromatous leprosy patients, whereas controls from the endemic area, including leprosy contacts and patients with tuberculosis, were serologically negative. The specificity and efficacy of the test may offer an advantage over previously used techniques.

Antibodies, Bacterial↗
PubMed1983

Definition of species specific and cross-reactive antigenic determinants of Mycobacterium leprae using monoclonal antibodies.

Four soluble antigens of Mycobacterium leprae have been identified using 12 murine monoclonal antibodies. Their specificity, taxonomic distribution and molecular nature were analysed by radioimmunoassays and by immunoblotting from polyacrylamide electrophoresis gels. A protein antigen MY1 (12K) reacted with one antibody (ML06) without demonstrable cross-reactivity for any of the other 20 tested species of mycobacteria. Another four antibodies which identified antigen MY2 revealed only a marginal degree of cross-reactivity with three other species of mycobacteria. Two antigens shared by several other mycobacteria species were: MY3 represented by five protein bands (35-70K) and a subtilisin resistant molecule MY4 (40-50K) with two distinct determinants and presumably of polysaccharide nature. The described monoclonal antibodies may represent novel valuable diagnostic reagents as well as tools for the purification of antigens which could be explored towards prophylactic or therapeutic immunization against leprosy.

Antibodies, Monoclonal↗
PubMed1983

Evaluation of a monoclonal antibody (TB72) based serological test for tuberculosis.

A serological test for tuberculosis (TB), based on competitive inhibition by human sera of antigen binding by a murine monoclonal antibody (TB72) has been performed using solid phase radioimmunoassay. The test was evaluated on sera from patients with pulmonary or extra-pulmonary active TB as well as from control hospitalized patients--half of whom had various chest complaints. Positive values were found in 74% of all or 55% of untreated active pulmonary TB. Patients with extrapulmonary TB segregated, whereby antibody titres were increased in cases of pleural, peritoneal, pericardial or bone infection but only marginal or negative values were found in the majority of patients with lymphatic and genitourinary infection. None of the subjects with suspected but excluded tuberculosis or sarcoidosis had demonstrable TB72 antibodies. Generally there was a positive correlation between the levels of TB72 like and 'total' Mycobacterium tuberculosis sonicate binding antibodies. In particular, the titre of sonicate binding antibodies did not exceed background levels in patients with active pulmonary tuberculosis who were negative in the TB72 competition test. None of these false negative patients received drug therapy whereas most patients with the highest antibody levels were under chemotherapy for 1-8 months prior to serum testing. The serodiagnostic value of the TB72 based competition test has been discussed.

Adult↗
PubMed1982

The use of murine monoclonal antibodies without purification of antigen in the serodiagnosis of tuberculosis.

A serum diagnostic test for tuberculosis has been devised on the basis of competitive inhibition by human sera of the binding of 125I-labelled murine monoclonal antibodies (Mabs) to a solid-phase bound pressate of M. tuberculosis. Five monoclonal antibodies binding to distinct antigenic determinants of the organism were used as structural probes which conferred their stringent combining site specificities to the polyclonal mixture of human antibodies. Sera from patients but not from healthy controls competed effectively with the binding of 125I-labelled Mabs to M. tuberculosis-coated polyvinyl plates. This inhibition technique eliminated the need for elaborate purification of antigen used in previous serological methods. Some Mabs gave considerably more positive results than others. The best combination of tests used 2 Mabs and yielded a positive result in 71% of 41 patients with smear-positive pulmonary tuberculosis. This approach is applicable in principle to the serodiagnosis of other human bacterial diseases.

Animals↗
PubMed1982

Study of antigenic structure and inhibition of activity of human growth hormone and chorionic somatomammotropin by monoclonal antibodies.

Distinct antigenic determinants were identified on native molecules of human growth hormone (hGH) and chorionic somatomammotropin (hCS) on the basis of competitive inhibition assays with eight murine monoclonal antibodies. Effective competition for antigen binding within a pair of antibodies indicated overlapping combining site specificities whereas a lack of competition suggested binding to sterically distinct structural moieties. An antigenic determinant, specific for hGH was detected by antibodies QA68 and NA27, whilst another marginally hCS-cross-reactive site was bound by NA71. Two distinct determinants fully expressed by either hGH or hCS were bound by antibody pairs NA39/EB2 and EB1/EB3 respectively, whereas a single hCS-specific determinant was recognized by antibody EB4. An unexpected reciprocal cross-inhibition of soluble antigen antibody complex binding was observed between antibodies reacting to distinct determinants, i.e. for NA27 towards NA39/EB2 and for NA71 towards EB1/EB3. These results were tentatively interpreted in terms of conformational changes of antigen when bound in soluble immune complexes, but an alternative explanation of steric hindrance cannot yet be excluded. The effect of monoclonal antibodies on the hormonal biological activity was investigated in a dose response study of the hormone-dependent growth stimulation of NB2 lymphoma cells in tissue culture. Although all eight antibodies were specifically growth-inhibitory, major quantitative differences in their efficacies have been observed. At limiting hormone doses antibodies EB2 NA39 were most effective whereas QA68 and NA71 were the most potent at excess hormone input. Various mechanisms operating through inhibition of hormone binding and/or modulation of cell receptor-bound complexes have been considered.

Antibodies, Monoclonal↗
PubMed1981

Allotype suppression in the chicken. II. Suppression in homozygous chickens with antiallotype antibody and allotype-disparate B cells.

Injection of heterozygous (M-1a/M-1b, G1g/G-1i) B 14-line chickens with antisera directed against either IgM-1a or IgM-1b induced suppression of the relevant IgM-1 and genetically linked IgG-1 allotypes, whereas a mixture of anti-M-1a and anti-M-1b antibodies failed to produce allotype suppression. Injection of anti-M-1 antiserum into M-1 homozygous chickens induced only a transient delay of a few days in the appearance and rise of serum IgM-1 levels. However, suppression of host allotypes was induced by injecting M-1, G-1 homozygous neonatal or embryonal recipients with anti-M-1 antisera together with B locus- histocompatible allotype-disparate spleen, bone marrow or bursal cells. The active cell type were donor B cells, which established chimerism in the injected host, whereas peripheral blood T lymphocytes from agammaglobulinemic donors were ineffective. Allotype suppression was attributed to a homeostatic control mechanism which is exerted by normal B cells (but not T cells) over B cell recruitment in anti-M-1 antibody-treated, immature hosts.

Animals↗