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Biomedical subjects

G Cambridge

Publications and source records attributed to G Cambridge.

At least 37 records · Page 2Linked to original sources
PubMed1997

Restricted expression of Fc gammaRIII (CD16) in synovium and dermis: implications for tissue targeting in rheumatoid arthritis (RA).

Interactions between immune complexes and immunoglobulin Fc receptors may contribute to inflammation in RA. Previous studies suggested that Fc gammaRIII (CD16) may be preferentially expressed in diseased synovial intima. The distribution of immunoreactive Fc gammaRIII was examined in normal fetal limb tissues, and both normal and selected abnormal samples of adult synovium and skin. In fetal limbs at 10-14 weeks gestation Fc gammaRIII was restricted to synovial intima. In normal adult synovium Fc gammaRIII was restricted to intimal cells. In inflamed synovia differential expression of Fc gammaRIII in the intima was less consistent. In both fetal and adult synovium Fc gammaRIII was largely restricted to cells expressing CD45 (leucocyte common antigen). Staining for Fc gammaRIII was, however, occasionally associated with CD45 intimal cells in fetal synovium. In both fetal and adult tissues cell membrane Fc gammaRIII was frequently closely associated with complement decay-accelerating factor (DAF), which is present on intimal fibroblasts and extracellular matrix. Fc gammaRIII expression was minimal in normal forearm dermis, but widespread on CD45+ cells in skin exposed to mechanical stress. In skin containing rheumatoid nodules, Fc-gammaRIII was preferentially expressed on palisading macrophages. These observations indicate that expression of Fc gammaRIII on macrophages may be involved in the susceptibility of connective tissues to immune complex-induced damage in RA. Colocalization of Fc gammaRIII and DAF in synovium may indicate an unrecognized functional interrelationship.

Adult↗
PubMed1997

Expression of molecules involved in B lymphocyte survival and differentiation by synovial fibroblasts.

The synovitis of rheumatoid arthritis (RA) is one of few pathological lesions in which B lymphocyte accumulation progresses to the extent of germinal centre formation. The present study was designed to assess the ability of synovial fibroblasts to express molecules implicated in B lymphocyte survival and differentiation, both in vivo, and in response to cytokines in vitro. Normal and diseased synovia were examined by indirect immunofluorescence. In all tissues synovial intimal fibroblasts showed co-expression of vascular cell adhesion molecule-1 (VCAM-1) and complement decay-accelerating factor (DAF) comparable to that of follicular dendritic cells (FDC), but not complement receptor 2 (CR2). In rheumatoid synovia, subintimal cells showed variable expression of VCAM-1 and DAF, with bright co-expression of VCAM-1, DAF and CR2 in lymphoid follicle centres. B lymphocytes, some of which were proliferating cell nuclear antigen-positive, were present in contact with subintimal cells expressing VCAM-1 with or without DAF or CR2. B lymphocytes were rarely present in the intimal layer, and, where present, showed fragmentation. In vitro, synovial fibroblasts exposed to tumour necrosis factor-alpha (TNF-alpha) in combination with interferon-gamma (IFN-gamma) showed enhanced expression of VCAM-1, in comparison with fibroblasts from skin and lung and, unlike skin and lung fibroblasts, also expressed DAF and CR2. These findings support the hypothesis that synovial targeting in RA involves an enhanced ability of synovial fibroblasts to support B lymphocyte survival. This appears to be dependent, not on the constitutive expression of VCAM-1 and DAF on intimal cells, but on the increased ability of subintimal cells to respond to proinflammatory cytokines, perhaps critically in the expression of VCAM-1.

B-Lymphocytes↗
PubMed1997

Autoantibodies to myeloperoxidase in systemic sclerosis.

OBJECTIVE: Although antimyeloperoxidase (MPO) antibodies provide a sensitive serological test for vasculitis, their significance in sera from a small proportion (about 10%) of patients with autoimmune rheumatic disease is controversial. Our aim was to determine the incidence of anti-MPO antibodies in sera from patients with systemic sclerosis (SSc) and their relation to renal disease. METHODS: Thirty-eight patients had limited cutaneous SSc (lSSc) and 43 diffuse cutaneous SSc, and within each group, 24 and 27 patients, respectively, had renal impairment (defined as stable creatinine clearance less than 60 ml/min). Six patients previously had had a scleroderma renal crisis. After screening for antineutrophil cytoplasmic antibodies (ANCA) by indirect immunofluorescence, the levels of IgM and IgG anti-MPO antibodies in 8 patients with SSc was determined by ELISA, with human MPO as antigen. RESULTS: Sera from 2 patients, both with lSSc and renal impairment, were perinuclear p-ANCA positive and had significant levels of circulating IgM and IgG anti-MPO antibodies. In one patient, anti-MPO antibodies appeared in the serum only after D-penicillamine was introduced, continued to rise after withdrawal of the drug, and fell only after immunosuppressive therapy. Renal biopsy confirmed vasculitis. The 2nd patient died of unrelated disease before further investigations could be performed. CONCLUSION: We suggest that circulating anti-MPO antibodies are not a feature of SSc per se and, if found, may indicate the presence of an unrelated pathology, such as idiopathic or drug induced vasculitis.

Adult↗
PubMed1996

Analysis of immunoglobulin variable region genes of a human IgM anti-myeloperoxidase antibody derived from a patient with vasculitis.

Circulating antibodies to myeloperoxidase (MPO) are associated primarily with pauci-immune glomerulonephritis and systemic vasculitis. Anti-MPO antibodies belong to a group of autoantibodies, anti-neutrophil cytoplasmic antibodies, that may play a pathogenic role in vasculitis. We have generated a human monoclonal anti-MPO antibody (E3-MPO) using peripheral blood lymphocytes from a patient with microscopic polyarteritis. Variable region gene analysis of E3-MPO showed that the VH region had 90% homology with the germ line gene VH4-21. E3-MPO was also shown to carry the 9G4 idiotope, which so far has been associated only with human antibodies that utilize the VH4-21 gene. The 9G4 idiotope was also expressed on anti-MPO antibodies in sera from the donor patient and from 4/7 additional patients with active, untreated vasculitis. The nucleotide sequences of both the variable heavy and light chains of E3-MPO showed evidence of an antigen-driven response.

Adult↗
PubMed1996

Autoantibodies to neutrophil granule proteins: pathogenic potential in vasculitis?

The discovery of circulating autoantibodies to neutrophil granule proteins (ANCA), which are present in a high proportion of patients with vasculitis, has revitalised both clinical and experimental research in this area. Although their antigen specificities and strong association with vasculitic diseases have now been established, the role of ANCA in the disease process is uncertain. This review is a brief outline of some of the clinical associations of ANCA, and describes interesting new avenues being taken in recent research which may provide an insight into how ANCA may contribute to vascular damage in patients with vasculitis.

Animals↗
PubMed1995

Antineutrophil antibodies in familial inflammatory bowel disease.

BACKGROUND/AIMS: Antineutrophil cytoplasmic antibodies have been reported to occur more frequently in healthy first-degree relatives of patients with ulcerative colitis than in healthy controls. The aim of this study was to determine their prevalence in families in which more than one member was affected with inflammatory bowel disease. METHODS: With use of an indirect immunofluorescence method, 168 affected members and 197 unaffected first-degree relatives in 56 such families were studied. RESULTS: Antibodies were detected in 46% of patients with ulcerative colitis without a positive family history and in 44% of those within families with several affected members. There was no evidence of clustering of antibodies in particular families. Within families in which both ulcerative colitis and Crohn's disease coexisted, antibodies were detected primarily in patients with ulcerative colitis. Antibodies were seldom present (3%) in those patients with Crohn's disease, whether they were familial or nonfamilial cases. Similarly, antibodies were seldom present (3%) in controls or the unaffected first-degree relatives of patients with inflammatory bowel disease. CONCLUSIONS: Antineutrophil cytoplasmic antibodies are associated with ulcerative colitis, and their presence is not increased in the first-degree relatives of patients with ulcerative colitis. They are more likely to be a consequence of the disease than a subclinical genetic disease marker.

Adolescent↗
PubMed1994

Autoantibodies to myeloperoxidase in idiopathic and drug-induced systemic lupus erythematosus and vasculitis.

Circulating antibodies to myeloperoxidase (MPO) have been described in a variety of vasculitic syndromes, drug-induced SLE and drug-induced nephritis. We have examined the autoantibody profile in acute sera from patients with antineutrophil cytoplasmic antibody-positive vasculitis (n = 8), drug-induced nephritis (n = 4), drug-induced lupus (n = 7), SLE (n = 27) and nephritis-associated with SLE (n = 17). Significant binding to purified MPO in ELISA was given by all sera from patients with vasculitis and drug-induced nephritis but ANA sought by indirect immunofluorescence on HEp-2 cells were not detected. Both anti-MPO and ANA were found in sera from patients with drug-induced lupus. Sera from patients with SLE or SLE nephritis did not contain high titres of anti-MPO antibodies but invariably contained ANA. Anti-MPO antibodies of both IgG and IgM classes were present in all sera from patients with drug-induced disease. Although the number of samples tested was small, sera from patients with drug-induced nephritis showed significantly greater median % binding of IgM to MPO compared with drug-induced SLE. Binding to MPO by IgG in these sera was not significantly different. These findings suggest that the mechanism of interaction between hydralazine and the immune system in the two drug-induced autoimmune diseases studied may contribute to their distinct clinical features.

Adolescent↗
PubMed1994

Anti-myeloperoxidase antibodies in patients with rheumatoid arthritis: prevalence, clinical correlates, and IgG subclass.

OBJECTIVES: To determine the prevalence and clinical associations of autoantibodies to myeloperoxidase (MPO) in an unselected series of well-characterised outpatients with rheumatoid arthritis (RA) and to compare the distribution of IgG subclasses of anti-MPO antibodies in these patients with that in patients with systemic vasculitis. PATIENTS AND METHODS: A study was made of 97 patients with RA, who have been seen regularly in this department for up to 20 years, and 29 patients with anti-neutrophil cytoplasmic antibody (ANCA) positive systemic vasculitis. Anti-MPO antibodies were detected using a direct-binding enzyme-linked immunosorbent assay (ELISA) with MPO from human granulocytes as antigen. The IgG subclass of anti-MPO antibodies was determined by ELISA using isotype specific monoclonal antibodies. RESULTS: Anti-MPO antibodies were detected in 12% of patients with RA. Six sera contained IgG anti-MPO antibodies only, 1 IgM only and 5 antibodies of both classes. In the patients with RA the predominant subclasses were IgG1 and IgG3: only 2 sera contained detectable IgG4 antibodies. This was in contrast to patients with vasculitis, in whom most sera contained IgG1, IgG3 and IgG4 anti-MPO antibodies. Anti-MPO antibodies in sera from both patient groups bound only to the native protein. None of the patients studied with RA had evidence of vasculitis affecting the nerves or kidney: three patients (1 positive for anti-MPO antibodies and 2 negative) had cutaneous vasculitis. In the patients with RA, positivity for anti-MPO antibodies was associated with nodules and number of active joints. Three patients with anti-MPO antibodies, and none without, had pulmonary fibrosis. CONCLUSIONS: Twelve per cent of a group of unselected outpatients with RA, but without evidence of major systemic vasculitis, had anti-MPO antibodies in their serum. Positivity for anti-MPO antibodies was more common in patients with nodular disease and lung involvement but not in patients with cutaneous vasculitis. IgG4 sub-class anti-MPO antibodies were present in 90% of sera from patients with ANCA-positive vasculitis and only 2/11 (18%) of anti-MPO antibody containing sera from patients with RA.

Adult↗
PubMed1993

Anti-endothelial cell antibodies in inflammatory bowel disease.

Antibodies to endothelial cells may be involved in the pathogenesis of vasculitic disorders. In view of recent evidence implicating intestinal vascular injury in the pathogenesis of inflammatory bowel disease, we have sought anti-endothelial cell antibodies in affected patients, examined their relationship to vascular injury, and tested their ability to mediate endothelial cell cytotoxicity in vitro. Anti-endothelial cell antibody levels were elevated in ulcerative colitis (P < 0.0001) and Crohn's disease (P < 0.05) compared with healthy controls. In ulcerative colitis, anti-endothelial cell antibody levels were related to disease activity and correlated with circulating levels of von Willebrand factor (r = 0.58, P < 0.01), a marker of vascular injury. Anti-endothelial cell antibodies, however, were not directly cytotoxic to endothelial cells in vitro. These data indicate, for the first time, an association between anti-endothelial cell antibody levels and vascular injury in vivo and suggest that they may be important in the pathogenesis of inflammatory bowel disease, particularly ulcerative colitis.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1993

Alpha-enolase: a novel cytosolic autoantigen in ANCA positive vasculitis.

Anti-neutrophil cytoplasmic antibodies (ANCA) in sera from patients with clinically proven vasculitis have been described as reacting with proteins present in the granules of human neutrophils. We have studied sera from 59 ANCA positive patients to further characterize the antibody response. In addition to the antigens previously identified in the vasculitic syndromes (myeloperoxidase and serine proteinase 3) the majority of these sera contained antibodies that reacted with a cytosolic extract of neutrophils on Western blots. Nearly 40% of these sera had antibodies directed against a cytosolic protein(s) of molecular mass 48 kD. This protein was purified from neutrophil cytosol by ammonium sulphate fractionation, anion exchange and reverse phase chromatography. Amino acid sequence analysis of a proteolytic fragment of this protein identified it as alpha enolase. The anti-enolase antibodies only recognized the alpha isoform and were present in sera giving either a pANCA or cANCA staining pattern by indirect immunofluorescence. Antibodies to alpha enolase were also found in sera from patients with systemic lupus erythematosus, particularly those with renal disease. We conclude that the antibody response in ANCA positive vasculitis is not restricted to neutrophil granule proteins.

Amino Acid Sequence↗
PubMed1993

Intercellular adhesion molecules in normal synovium.

The vasculature of normal synovium and skin has been examined for the presence of molecules believed to be involved in intercellular adhesion and whose expression on endothelial cells in vitro is known to be upregulated by cytokines. Synovium was obtained from clinically and histologically normal joints removed during amputations for proximal sarcomata. Skin was obtained from healthy volunteers. Cryostat sections of tissues were assessed by immunohistochemistry and microdensitometry for the presence of E-selectin using monoclonal antibody 1.2B6, intercellular adhesion molecule-1 (ICAM-1) using monoclonal antibody 6.5B5 and vascular cell adhesion molecule (VCAM-1) using monoclonal antibody 1.4C3. Both E-selectin and ICAM-1 were present on a proportion of normal synovial venules but at a level comparable to or lower than that found on dermal vessels. (Staining intensities given as mean absorption indices: superficial synovium 1.2B6: 9.9 +/- 11.4, 6.5B5: 10.2 +/- 12.0, deep synovium 1.2B6: 6.6 +/- 9.9, 6.5B5: 24.6 +/- 15.7, skin 1.2B6: 13.1 +/- 16.6, 6.5B5: 36.4 +/- 12.9.) E-selectin expression was most prominent on small superficial venules in synovium and ICAM-1 most strongly expressed on larger, deep venules. VCAM-1 was found at low levels on cells associated with vessel walls but no significant endothelial staining was seen in either type of tissue. VCAM-1 was also present on cells of the synovial lining layer. Some of the findings in synovium could have been attributable to tumour related cytokine release, but the consistency of findings and comparability to skin suggest that this is relatively unlikely.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Development of an in vitro hepatotoxicity assay for assessing the effects of chronic drug exposure.

We have used the human hepatoma cell line HepG2 to compare the hepatotoxic effects of acute (24 hr) and chronic (up to 10 days) exposure to amitriptyline, paracetamol and ondansetron. In acute exposure studies, hepatotoxicity was assessed by the sulforhodamine B protein staining method, where amitriptyline and paracetamol produced 50% hepatotoxicity at concentration of 30 microM and 7 mM, respectively, while ondansetron was non-hepatotoxic at 100 microM, the highest concentration used. In chronic exposure studies, the morphology of HepG2 cells was assessed by phase microscopy every 2 days and the compounds, at concentrations determined from the acute assay, were added fresh every 2 days. Chronic exposure to amitriptyline and paracetamol produced significant morphological changes in HepG2 cells at 3 microM and 1 mM respectively, concentrations which had no significant effect in the acute assay. Ondansetron (100 microM) produced only slight morphological changes in the cells after 10 days of culture. The combination of acute and chronic drug exposure assays with HepG2 cells represents novel in vitro systems for the hepatotoxicological assessment of drugs intended for human use.

Acetaminophen↗
PubMed1992

Anti-neutrophil antibodies in inflammatory bowel disease: prevalence and diagnostic role.

Anti-neutrophil antibodies have been shown in sera from patients with a variety of inflammatory diseases. Those reacting with components of neutrophil cytoplasm are associated with systemic vasculitis. Both nuclear and perinuclear staining patterns on human neutrophils have been reported using sera from patients with inflammatory bowel disease. We have evaluated the reactivity against human neutrophils of sera from 100 patients with inflammatory bowel disease, 14 disease controls, and 20 normal volunteers. Altogether 27/50 (54%) sera from patients with ulcerative colitis contained antibodies that reacted with cytospun ethanol fixed neutrophils compared with 5/50 (10%) from Crohn's disease (p less than 0.001) and 0/34 control sera (p less than 0.001). All seven sera from patients with proctitis alone were negative (p less than 0.01). There was no correlation between presence or titre of anti-neutrophil antibodies and either disease activity or treatment. Positive sera gave three different staining patterns on human neutrophils. The predominant pattern was perinuclear (17/32); 12 sera gave a cytoplasmic and three a homogeneous nuclear staining pattern. None of the patients or the controls had antibodies to myeloperoxidase, elastase, or serine proteinase 3, all of which are recognised by anti-neutrophil cytoplasmic antibodies. Only 2/27 sera positive by indirect immunofluorescence reacted with an extract of neutrophil primary granules. In conclusion, anti-neutrophil antibodies occur more commonly in ulcerative colitis than in Crohn's disease or control subjects and the anti-neutrophil antibodies found in inflammatory bowel disease are different from those associated with vasculitis.

Adult↗
PubMed1992

Idiopathic pulmonary haemosiderosis: a form of microscopic polyarteritis?

Idiopathic pulmonary haemosiderosis remains a diagnosis of exclusion in patients who present with pulmonary alveolar haemorrhage. Systemic vasculitis developed in a patient with an eight year history of idiopathic pulmonary haemosiderosis. The diagnosis was confirmed by a rising titre of antineutrophil cytoplasmic antibodies directed against myeloperoxidase. Treatment with immunosuppressive agents resulted in complete resolution of symptoms and suppression of the antibodies. Measurement of antineutrophil cytoplasmic antibodies is recommended for all patients with pulmonary alveolar haemorrhage syndromes.

Adult↗