PubMed Health⌕ Search

Biomedical subjects

A R Coates

Publications and source records attributed to A R Coates.

At least 55 records · Page 3Linked to original sources
PubMed1989

The 45 kilodalton molecule of Mycobacterium tuberculosis identified by immunoblotting and monoclonal antibodies as antigenic in patients with tuberculosis.

The object of this study was to discover new M. tuberculosis antigens which are recognized by patients with tuberculosis, because effective serodiagnostic tests are likely to require combinations of different antigens. In our early experiments using immunoblotting, the findings suggested that human sera from smear-negative tuberculosis patients bound to an antigen in the 45 kDa region. Subsequently, estimates of molecular weight in the immunoblots confirmed that the murine monoclonal antibody (MAB) HGT-6 and sera from patients both recognized the same 45 kDa molecule. An antibody-antibody competition assay between MAB HGT-6 and sera from smear-positive tuberculosis patients yielded a positive result in 23 out of 43 sera from patients, but in only four out of 23 from controls. This is further evidence that the 45 kDa antigen is recognized by tuberculous patients. We analysed whether a combination of the 45 kDa antigen results and those of known antigens might better discriminate between minimal smear-negative disease and healthy controls than could test with single antigens. There is no clinically useful laboratory test for smear-negative tuberculosis. In immunoblotting, combining the results with the 65, 45, 38 and 10 kDa antigens gave the best discrimination. This suggests that future serodiagnostic tests for minimal disease, such as the antibody-antibody competition assay, should contain a MAB against the 45 kDa antigen and possibly also against the 10 kDa antigen.

Antibodies, Monoclonal↗
PubMed1989

Serum monoclonal antibodies derived from patients with multiple myeloma react with mycobacterial phosphoinositides and nuclear antigens.

The sera of 46 patients with multiple myeloma were examined for the presence of anti-tuberculosis (TB) glycolipids antibodies. In positive sera samples, anti-polynucleotides, anti-histones, anti-cardiolipin, anti-Sm and anti-RNP activities were sought. Antibodies against three different mycobacterial glycolipids were detected in 10 of the 46 sera. Three (P429, P557, P5) showed high titres of antibodies against all three different TB glycolipids. Of the 10 reactive samples, two antibodies were purified (P429, P557). P557 reacted with various polynucleotides and other antigens tested (Sm, RNP, cardiolipin, histones). One immunoglobulin (P207) which showed high activity against Sm and RNP had no activity against TB glycolipids and was employed as a control. The cross-reactivity between mycobacterial glycolipids and the nuclear antigens was further established by bi-directional competition assays with P429 and P557. Our study shows a high incidence (22%) of anti-TB glycolipids antibodies in sera of patients with monoclonal gammopathies, some of which show anti-DNA and other anti-nuclear antigens activities. This is additional evidence for the mycobacterial-nuclear antigen cross-reactivity which may suggest a possible role of infection (e.g., tuberculosis) in autoimmune diseases.

Antibodies, Antinuclear↗
PubMed1988

Predictions of linear T-cell and B-cell epitopes in proteins encoded by HIV-1, HIV-2 and SIVMAC and the conservation of these sites between strains.

An important consideration in the design of vaccines to prevent HIV-1 infection effective against different strains is the amino acid sequence conservation of antigenic determinants. Even one amino acid change can destroy the antigenicity of a site for the antibody or T-cell receptor. The comparisons of predicted T- and B-cell epitopes between human HIV-1, HIV-2 and monkey SIVMAC AIDS viruses are presented. The three major gene products (env, gag and pol) were examined. A number of epitopes were identical between strains of HIV-1. Our analysis highlights the problem of designing an effective HIV-1 and HIV-2 vaccine and also the problem of testing human vaccines in monkey models.

Amino Acid Sequence↗
PubMed1988

A novel human macrophage-activating factor: distinction from interferon-gamma (IFN-gamma) and granulocyte-macrophage colony-stimulating factor (GMCSF).

Culture supernatant from a human T-cell leukemia virus type I (HTLV-1)-infected cell line, DGA-1, contained a novel macrophage-activating factor (MAF). This MAF was antigenically and functionally distinct from interferon-gamma (IFN-gamma) and from granulocyte-monocyte colony-stimulating factor (GMCSF). Potential contaminants such as bacterial lipopolysaccharide (LPS), Mycoplasma spp, and HTLV-1 were not responsible for this MAF activity. The DGA-1 MAF was secreted constitutively and the cell line grew well in the absence of growth factors such as interleukin-2, mitogen, or antigen. This cell line should provide a good source of this MAF for further purification and characterization.

Animals↗
PubMed1987

Prediction of antigenic determinants and secondary structures of the major AIDS virus proteins.

Criteria for the design of peptide vaccines to prevent AIDS are presented. The best vaccine candidates contain both B and T lymphocyte-defined epitopes in regions conserved in sequence between viral isolates. We propose that attention should focus on proteins specified by the gag and, possibly, pol genes in addition to the env gene envelope glycoproteins being actively studied. The predictions of B- and T-epitopes are refined by consideration of secondary structure prediction and inter-isolate sequence variability to suggest peptides from env, gag and pol that would be the best vaccine candidates.

Amino Acid Sequence↗
PubMed1987

Low serum antimycobacterial glycolipid antibody titers in the sera of patients with systemic lupus erythematosus associated with central nervous system involvement.

Antibodies which bind to glycolipids derived from Mycobacterium tuberculosis were sought in the sera of patients with systemic lupus erythematosus (SLE), with and without neurological disease, patients with active tuberculosis and normal controls. A significantly lower activity against the mycobacterial glycolipids was detected in the sera of patients with SLE with neurological involvement compared to other patients with SLE or controls. We suggest that low antibody levels against mycobacterial glycolipids may be useful in the diagnosis of patients with SLE in whom involvement of the central nervous system is suspected.

Antibodies, Bacterial↗
PubMed1987

ELISA measurement of antibody titer to purified protein derivative and mycobacteria-derived phosphoglycolipids: tool for diagnosing active pulmonary tuberculosis.

There is a continuous search for a rapid, efficient and reliable serodiagnostic technique for active tuberculosis (TB). Using ELISA (enzyme-linked immunosorbent essay) we have determined antibodies reactive to purified protein derivative (PPD) and two phosphoglycolipids extracted from Mycobacterium bovis cell wall, phosphatidyl inositol dimannoside (PID) and phosphatidyl inositol pentamannoside (PIP). Twenty-one patients of Ethiopian origin with active pulmonary TB and 20 healthy control subjects vaccinated with BCG in infancy were evaluated. A significantly higher level of immunoglobins reactive with the antigens was found among the patients with active pulmonary TB. The mean +/- SD of the OD units (x 10(3)) recorded in the sera of TB patients compared with control subjects were as follows: using PPD 250 +/- 210 vs. 120 +/- 150 (P less than 0.025); with PID 1,150 +/- 470 vs. 750 +/- 150 (P less than 0.01); and with PIP 1,170 +/- 500 vs. 780 +/- 160 (P less than 0.025). Accordingly, the sensitivity and specificity levels were: with PPD 81 and 75%, with PID 82 and 80% and with PIP 73 and 70%, respectively. Much more accuracy can be obtained by calculating the results of reactivity toward the combined free antigen assays. It is suggested that ELISA using mycobacterial derived antigens might be useful in the diagnosis and screening of active pulmonary TB in large populations, due to its rapidity and simplicity.

Antibodies, Bacterial↗
PubMed1986

Recombinant interferon-gamma and chemotherapy with isoniazid and rifampicin in experimental murine tuberculosis.

Viable bacterial counts in the lungs and spleens of mice infected intravenously with Mycobacterium tuberculosis, strain H37Rv were reduced by intravenous recombinant murine interferon-gamma (IFN-gamma) 1000-5000 u, but not by 200 u. Reduction in counts was greatest when IFN-gamma was given 1 day before infection and was not increased by additional doses in the preceding 2 days. The effect was complete in 1 day and was not increased by successive doses during the next week. Giving IFN-gamma in multilamellar liposomes further reduced the spleen viable counts, but this appeared due to the liposomes themselves and not to encapsulation of IFN-gamma within them. Only a minimal reduction in organ viable counts, not statistically significant, occurred when IFN-gamma was given 5 days after infection. Although IFN-gamma alone and isoniazid 25 mg/kg alone reduced the organ viable counts, combined treatment with IFN-gamma and isoniazid was no more bactericidal than isoniazid alone. Similarly, the bactericidal activity of rifampicin 25 mg/kg was not increased by simultaneous administration of IFN-gamma. There seems little likelihood that IFN-gamma would increase the efficacy of the early stages of the chemotherapy of tuberculosis.

Animals↗
PubMed1986

Monoclonal anti-tuberculosis antibodies react with DNA, and monoclonal anti-DNA autoantibodies react with Mycobacterium tuberculosis.

Classical models of experimental autoimmune diseases, such as adjuvant arthritis entail the use of mycobacteria. Furthermore, BCG immunotherapy may be followed by arthritic symptoms. To test the infection-autoimmunity relationship of mycobacteria, we used monoclonal antibodies raised against M. tuberculosis and against DNA. Murine monoclonal anti-TB antibodies were found to react with ssDNA, dsDNA and other polynucleotides. Monoclonal anti-DNA autoantibodies derived from patients and mice with SLE bound to three glycolipids shared among all mycobacteria and derived from mycobacterial cell wall. Prior incubation of the antibodies with ssDNA and other polynucleotides or with glycolipid antigens inhibited binding. These results indicate that infecting mycobacteria share antigens with human tissue, thus accounting in part for the production of autoantibodies in mycobacterial infections.

Animals↗
PubMed1985

A novel semi-automated technique for measuring inhibition of intracellular mycobacterial growth by macrophage activating factor.

We have developed a rapid, in vitro method for measuring T lymphocyte-derived macrophage activating factor (MAF) which inhibits the proliferation of Mycobacterium microti within macrophages. This MAF may be important in the control of mycobacterial disease in vivo. Because MAFs are a heterogeneous group of factors with different activities there is a need for assays which are relevant to specific macrophage effector functions. The existing assays for MAFs which are relevant to killing or inhibition of replication of mycobacteria within macrophages are currently too cumbersome or time consuming for the large scale screening required for their detection and purification. In our assay, monolayers of mouse macrophages were infected with the murine pathogen M. microti and were cultured for 6 days with MAF or control medium. The intracellular bacteria were stained with auramine-O and were quantified using epifluorescence microscopy with television image analysis. Total assay time was one-seventh that of viable count methods, and image analysis estimates of bacterial loads are quicker and more objective than visual counts.

Animals↗
PubMed1985

Characterization of the specificity of monoclonal antibodies against Mycobacterium tuberculosis by crossed immunoelectrophoresis.

The specificity of monoclonal antibodies against Mycobacterium tuberculosis was determined by crossed immunoelectrophoresis. Radiolabelled, non-precipitating monoclonal antibody was incorporated in the top gel together with unlabelled polyvalent, precipitating anti-bacillus Calmette-Guérin (BCG) antibody. Inclusion of labelled antibody in individual precipitate lines was demonstrated by autoradiography. Each monoclonal antibody was localized in a single precipitate line: antibody TB73 reacted with BCG antigen 56; TB71 and TB72 reacted with BCG antigen 78; and TB78 reacted with BCG antigen 82. The technique permits precise determination of the specificity of monoclonal antibodies at the level of reactivity with native immunogenic components of complex microorganisms without prior antigen purification.

Animals↗
PubMed1984

Secretion of a macrophage-activating factor distinct from interferon-gamma by human T cell clones.

Supernatants from clones of human T lymphocytes that were responding to a purified Mycobacterium tuberculosis antigen were able to activate macrophages and macrophage-like myeloma cells (U937) to release increased amounts of the microbicidal agent hydrogen peroxide. The activity was not neutralized by monoclonal antibody against interferon-gamma (IFN-gamma), was greater than could be accounted for by the IFN-gamma activity in the supernatants, and was separated from IFN-gamma by high performance liquid chromatography. It is evident that IFN-gamma is not the only macrophage activator released by T lymphocytes responding to microbial antigen, and may not even be the main one to enhance antimicrobial activity in infections such as tuberculosis.

Antibodies, Monoclonal↗
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↗