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G A Rook

Publications and source records attributed to G A Rook.

At least 127 records · Page 7Linked to original sources
PubMed1989

The role of cytokines in the immunopathology of tuberculosis, and the regulation of agalactosyl IgG.

Tuberculosis is characterised by necrosis in the lesions and in skin-test sites, and by fever and weight loss. In contrast, other diseases with chronic T cell mediated responses, such as uncomplicated leprosy and sarcoidosis, have non-necrotising lesions with little systemic upset. Crude sonicates of M. tuberculosis and M. leprae prepare skin sites for TNF-mediated damage via a pathway which unexpectedly appears to involve CD8+ T cells, and both mycobacteria contain potent triggers of TNF release (lipoarabinomannan and peptidoglycan derivatives). These observations can partially explain the pathology of tuberculosis, but fail to explain why similar events do not normally occur in leprosy. It now seems likely that the answer lies in the existence of novel regulatory pathways. A recently recognised correlate (or consequence) of diseases characterised by T cell-dependent tissue-damaging pathology and cytokine release, is an increase in the level of agalactosyl IgG. This behaves like a T cell-dependent acute phase reactant, and is raised in tuberculosis, rheumatoid arthritis, and Crohn's disease, but not in sarcoidosis or uncomplicated leprosy. Thus it may act as a marker for a type of pathology of very broad significance, though its functional role remains obscure.

Animals↗
PubMed1989

Membrane N-acetylglucosamine: expression by cells in rheumatoid synovial fluid, and by pre-cultured monocytes.

After 21-48 h in culture, 2-8% of human peripheral blood monocytes strongly express terminal N-acetylglucosamine (GlcNAc) on their membranes. This can be detected with a monoclonal antibody selected for binding to asialo-agalacto-fetuin, and is eliminated by incubating the cells in pure N-acetylglucosaminidase. Expression of GlcNAc is transient, and can no longer be detected by day 4. These cells are a subset of macrophages since they are positive for non-specific esterase and stained by the monoclonal antibody EBM 11. GlcNAc-positive cells showing double staining with monoclonal antibodies UCHM1 and RFD7 were detected. Their numbers were not influenced by the addition of GM-CSF, IFN-gamma, 1,25-(OH)2 cholecalciferol or indomethacin. Macrophages which give membrane staining for terminal GlcNAc were also found in rheumatoid synovial fluid, and in synovial tissue, though in the peripheral blood their frequency was the same in samples from normal donors and from patients with rheumatoid arthritis. Immunoblots of 24-48-h monocyte cultures or of fresh synovial fluid cells using the anti-GlcNAc monoclonal, show the anticipated agalactosyl IgG heavy chains, and an additional band of 70-80kDa.

Acetylglucosamine↗
PubMed1989

An association between Gc (vitamin D-binding protein) alleles and susceptibility to rheumatic fever.

Rheumatic fever is associated with exaggerated activity of B cells with massive production of antibody to the Group A streptococcus. Gc (vitamin D-binding protein) is constitutively expressed on B-cell membranes in association with membrane immunoglobulin, and could be involved in cell activation. We therefore looked for associations between the three major Gc alleles and susceptibility to rheumatic fever in a homogeneous Arab population. Patients with tuberculosis or rheumatoid arthritis and control donors, were studied in parallel. Allele frequencies in the controls, rheumatoid and tuberculosis patients were identical to those found in a previous study of normal Arab donors. However, there was a striking association between Gc2 and rheumatic fever. This allele was twice as common in these patients as in controls (p = 0.0024), and was present in 56.4% of all rheumatic fever patients.

Alleles↗
PubMed1989

A transient rise in agalactosyl IgG correlating with free interleukin 2 receptors, during episodes of erythema nodosum leprosum.

The proportion of oligosaccharide chains on the Fc fragment of IgG which terminate with N-acetylglucosamine and not galactose (%GO) has previously been shown to be raised in rheumatoid arthritis (RA), Crohn's disease (CD) and tuberculosis (Tb), but to be normal in sarcoidosis (SA), and in both lepromatous and tuberculoid leprosy. However we have now studied %GO in sequential serum samples collected from lepromatous leprosy patients undergoing episodes of erythema nodosum leprosum (ENL). During ENL %GO is transiently raised, and this rise parallels an increase in circulating interleukin 2 receptors (IL-2R). These findings confirm that changes in T cell function occur during ENL. Moreover it appears that %GO rises when there is, simultaneously, T-cell-mediated tissue damage and an acute phase response (RA, CD, Tb, ENL), but not when there is an acute phase response without major T cell involvement, or chronic T cell activity alone (SA, and tuberculoid leprosy). We suggest therefore that %GO is an indicator of a type of T cell activity with broad immunopathological implications.

Acetylglucosamine↗
PubMed1988

The secreted antigens of Mycobacterium tuberculosis and their relationship to those recognized by the available antibodies.

Proteins secreted by strains of Mycobacterium tuberculosis during short-term, zinc-sufficient batch culture were identified in order to define antigens likely to be relevant to the pathogenesis of human disease. [35S]Methionine-labelled proteins in supernatants of 4-7 d cultures were separated by PAGE under both denaturing and non-denaturing conditions, and the position of labelled material was determined. Secreted protein patterns of M. tuberculosis were quite similar to those of Bacillus Calmette-Guérin (BCG) but differed by the absence of the 46 kDa dimeric protein specific to BCG and by the presence in large amounts of a 23 kDa protein which, when denatured, gave 13 kDa subunits. This 13 kDa subunit protein constituted up to 20% of secreted proteins in classical strains of M. tuberculosis of phage type B but was not detected in phage type I strains from South India. This may be relevant to the different pathogenicity of these strains. Western blot analysis showed that antigens defined in supernatants of short-term (3 d) cultures of M. tuberculosis constituted a small subset of those seen in supernatants of organisms cultured for longer periods. One of the secreted proteins has the interesting property of binding to fibronectin. The available monoclonal antibodies and antisera have been used to identify lines on immunoblots corresponding to the secreted/released antigens of M. tuberculosis. The present findings suggest that there are major secreted antigens to which antibodies do not yet appear to have been produced experimentally.

Antibodies, Monoclonal↗
PubMed1988

Attachment of mycobacteria to fibronectin-coated surfaces.

This report investigates the extent of the expression of fibronectin (FN) binding properties among the mycobacteria and provides preliminary characteristics of the bacterial molecule(s) mediating attachment. Eight BCG substrains, three Mycobacterium tuberculosis strains and four other mycobacterial species all expressed FN-binding capacity. Treatment of organisms with detergent prior to the binding assay destroyed the FN-binding capacity of BCG but not that of Staphylococcus aureus. Trypsin pretreatment eliminated the FN-binding capacity of both BCG and S. aureus. [35S]Methionine-labelled material in supernatants from BCG and M. tuberculosis cultures attached to FN-coated surfaces. These culture supernatants inhibited the attachment of BCG but not S. aureus to FN-coated surfaces. This inhibitory activity of the supernatants was removed by affinity chromatography on FN-Sepharose but was not affected by similar passage over a control column (human serum albumin attached to Sepharose). These results demonstrate that the ability to bind FN is present in all mycobacterial species tested and suggest that attachment is mediated by trypsin-sensitive cell-surface component(s).

Fibronectins↗
PubMed1988

Characterization of fibronectin-binding antigens released by Mycobacterium tuberculosis and Mycobacterium bovis BCG.

Fibronectin (FN)-binding antigens are prominent components of short-term culture supernatants of Mycobacterium tuberculosis. In 3-day-old supernatants, a 30-kilodalton (kDa) protein was identified as the major FN-binding molecule. In 21-day-old supernatants, FN bound to a double protein band of 30 and 31 kDa, as well as to a group of antigens of larger molecular mass (57 to 60 kDa). FN-binding molecules in this size range, but not of 30 to 31 kDa, were also found in sonicates. We showed that the 31- and 30-kDa FN-binding bands correspond to components A and B of the BCG85 complex, previously shown to be abundant in culture supernatants of Mycobacterium bovis BCG. Thus, a polyclonal antibody to the BCG85 complex bound to the 30- and 31-kDa antigens and inhibited binding of FN to them on immunoblots of the culture filtrates. Similarly, FN bound to the purified components of the BCG85 complex, and this binding was blocked by the antibody. A monoclonal antibody, HYT27, also bound both to the BCG85 components A and B and to the 30- and 31-kDa FN-binding molecules of M. tuberculosis, but it did not block the binding of FN. Related molecules appear to be present on the surface of BCG and to mediate the binding of BCG to FN-coated plastic surfaces, since this binding could also be blocked by the polyclonal anti-BCG85 antibody and by the purified components of BCG85, particularly component A, but not by monoclonal antibody HYT27. The binding of these mycobacterial antigens to FN appears to be of very high affinity, and we suggest that this property of major secreted antigens of M. tuberculosis indicates an important role in mycobacterial disease and in the binding of BCG to tumor cells during immunotherapy of bladder cancer.

Antigens, Bacterial↗
PubMed1988

A monoclonal antibody raised by immunising mice with group A streptococci binds to agalactosyl IgG from rheumatoid arthritis.

It was shown recently that the IgG of patients with rheumatoid arthritis tends to lack the terminal galactose normally present on the conserved N-linked oligosaccharide situated on the CH2 domain. This results in the exposure of a terminal N-acetylglucosamine linked beta 1-2 to mannose. It is reported here that mice immunised with the peptidoglycan/polysaccharide complex of group A streptococci can be used as a source of monoclonal antibodies binding to this epitope. It may be significant that the organism responsible for rheumatic fever evokes antibodies binding to an abnormality of IgG found in rheumatoid arthritis.

Acetylglucosamine↗
PubMed1988

Specificity of antibodies secreted by hybridomas generated from activated B cells in the mesenteric lymph nodes of patients with inflammatory bowel disease.

Hybridomas have been prepared from active B cells in lymphoid tissue draining lesions of Crohn's disease (CD) and ulcerative colitis (UC), by fusion of fresh mesenteric lymph node suspensions with the murine JK myeloma. Two hundred and fifty nine immunoglobulin secreting hybridomas have been obtained from nine patients. The antibodies have been screened for binding to food antigens, sections of human gut, and bacteria including two unidentified acid fast isolates from CD lymph nodes. Autoantibodies, and antibodies to food antigens implicated by others in the aetiology of CD were rare, comprising 1.2%, and 2.5% respectively. Most donors yielded none of these. Thus neither food antigens nor autoantigens are major antigenic stimuli in nodes draining inflammatory bowel disease. On the other hand between 19% and 83% of supernatants from different donors bound to one or more bacterial genus. The mycobacteria and the CD isolates were amongst the genera to which most antibodies bound, though binding to E coli was more frequent. Significantly more CD than UC derived supernatants bound to BCG. As mycobacteria are not though to be part of the normal bowel flora, the high percentage of hybridomas secreting antibodies which bind to this genus is surprising.

Adult↗
PubMed1988

Antibody levels to mycobacteria in relation to HLA type: evidence for non-HLA-linked high levels of antibody to the 65 kD heat shock protein of M. bovis in rheumatoid arthritis.

We previously reported DR2 and DR7-associated regulation of antibody binding to mycobacteria in rheumatoid arthritis sera (RA), but not in tuberculosis (Tb). An extensive analysis of antibody to mycobacteria in matched normal sera, in relation to both HLA class I and class II has revealed no class II correlations, confirming that the original findings were due to RA. There was however a very strong association between IgM binding to M. tuberculosis and Cw1 (P = 0.0004). RA patients have strikingly raised levels of IgG (but not of IgA or IgM) binding to the 65 kD heat shock protein of M. tuberculosis, recently implicated in the pathogenesis of adjuvant arthritis in the rat. Remarkably, levels in RA were significantly higher even than in tuberculosis. Levels of this antibody showed no HLA associations. Thus the 65 kD antigen does not account for the DR7, and DR2 associations of IgM and IgA binding to mycobacteria reported previously, but does suggest a role for cross-reactive autoimmunity in RA.

Adolescent↗
PubMed1988

HLA-DR-associated isotype-specific regulation of antibody levels to mycobacteria in rheumatoid arthritis.

Using sera from 75 healthy donors, 68 rheumatoid arthritis (RA) patients, and 85 tuberculosis (TB) patients, we have examined the level of antibody of the three major classes binding to seven mycobacterial species, and to three control antigens. The major findings are that IgM binding to mycobacteria is reduced in RA patients who have HLA-DR7 (P = 0.008 for M. tuberculosis antigen), and that IgA binding to mycobacteria is reduced in RA patients who have HLA-DR2 (P = 0.007 for M. tuberculosis; P = 0.0004 for M. nonchromogenicum). These associations were not seen in TB, and were restricted to these antibody isotypes. We believe this is the first report of isotype specific Class II MHC-associated regulation of antibody levels in man. A possible interpretation of our data is that patients bearing these haplotypes are recognizing suppressor epitopes common to all the mycobacterial species tested. Since DR2 and DR7 have recently been shown to be associated with a significantly reduced risk of RA, our findings are compatible with the view that changes in immune responsiveness to mycobacterial antigens, or to autoantigens which cross-react with them, are relevant to RA.

Adolescent↗
PubMed1988

Induction of delayed-type hypersensitivity responses to PPD: dendritic cells in synergy with 5-hydroxytryptamine can substitute for macrophages.

We describe the use of 5-hydroxytryptamine (5HT) as an adjuvant in the induction of the delayed-type hypersensitivity (DTH) response to purified protein derivative (PPD). Based upon our previous studies with antigen-pulsed macrophages (M phi), we have shown that both the Day 2 early (2 hr) reaction and the Day 3 (24 hr) reaction are augmented if 5HT is incorporated into the priming injection. Furthermore, we have confirmed that in contrast to M phi, antigen-pulsed dendritic cells (DC) fail to prime the early (2 hr) component of DTH. However, DC do prime the early response if injected along with 5HT. A peripheral 5HT antagonist, ICS 205-930, inhibits both the M phi-mediated and the 5HT/DC-primed reactions. These findings support the hypothesis that DTH reactions require a cascade of both inflammatory and immunological signals, and that in mice vascular permeability mediated via 5HT is important in the early phase of the reaction.

Adjuvants, Immunologic↗
PubMed1987

A simple new method for using antigens separated by polyacrylamide gel electrophoresis to stimulate lymphocytes in vitro after converting bands cut from Western blots into antigen-bearing particles.

The individual antigenic components present in microgram quantities of complex mixtures can be separated reproducibly by polyacrylamide gel electrophoresis and transferred onto nitrocellulose blots. We report that the ng quantities of antigen present in single lines cut from such Western blots can be used to induce maximal lymphoproliferative responses in 30-60 microtitre wells. In order to achieve this the excised lines of antigen-bearing nitrocellulose sheet must be converted into antigen-bearing particles small enough to be engulfed by macrophages. We describe optimal conditions and discuss the applications of this technique.

Antigens, Bacterial↗
PubMed1987

Unexpected findings amongst the skin test responses to mycobacteria of BCG vaccinated Kuwaiti school children.

A multiple skin test survey was carried out in Kuwait on 1200 school children aged 8-11 years, and on 1228 children aged 12-16 years. With only 15 exceptions, all these children had received vaccination with Japanese BCG just before they started school, 5 years and 9 years earlier respectively. Tuberculin positivity was almost 90% in both groups, with a mean response size of 8.7 mm. This was associated with remarkably high responsiveness to many of the other mycobacterial species investigated. Since this high reactivity was also to Mycobacterium ulcerans, a species most unlikely to be present in Kuwait, it is proposed that this might be due to responsiveness to group ii antigen which is present in all slow growing species. Only M. flavescens and M. rhodesiae amongst the fast growing species, were absent as sensitising organisms. After correction for the supposed reactivity to group ii antigen, M. avium B, M. gordonae, M. ulcerans and M. xenopi amongst the slow growing species, also appeared to be absent from the Kuwait environment. The species most commonly encountered were M. leprae, M. chitae, M. neoaurum, M. diernhoferi, and M. vaccae in this order. This was a remarkable finding for a country assumed to be poor in contact with environmental species, and known to have a very low prevalence of leprosy. As previously reported from Iran, but not confirmed in other places, there was a 95% correlation between responsiveness to Leprosin A and Vaccin. Amongst the slow growing species M. avium A, M. intracellulare, and M. kansasii appear to be frequent sensitising agents, in common with many other places.

Adolescent↗
PubMed1987

The immune response in two populations of wild badgers naturally infected with bovine tubercle bacilli.

This study describes the immune responses of two defined badger populations; one from East Sussex and another from Staffordshire. The mean in vitro lymphoproliferative response, of all infected badgers from both areas, to Glaxo BCG, was significantly greater than that of healthy animals. The infected badgers had significantly higher antibody levels against mycobacterial antigens, especially New Tuberculin, than did the healthy animals. All the healthy and tuberculous badgers from the Staffordshire area were invariably unreactive to the various preparations used for skin-testing. However, in the East Sussex area, positive reactions were obtained in 10 out of 37 healthy and 7 out of 10 infected animals. This is the first account of positive skin tests in free living badgers. These results support the concept that badgers infected with bovine tubercle bacilli pass through an immunological spectrum throughout much of which they are unlikely to be important sources of infection. In the early stages, tubercle bacilli are excreted from infected wounds, whereas in the later stages, failure of cell-mediated immunity results in excretion of tubercle bacilli from other sites and the badger becomes a potent source of infection.

Animals↗