Search PubMed⌕ Search

Biomedical subjects

C M Lockwood

Publications and source records attributed to C M Lockwood.

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

The glomerular basement membrane defect in Alport-type hereditary nephritis: absence of cationic antigenic components.

Alport-type hereditary nephritis is a familial disorder which results in progressive renal insufficiency and sensorineural hearing loss. It is thought to result from a biochemical defect affecting basement membranes. To study this further, non-collagenous components of type IV collagen were prepared from the glomerular basement membrane (GBM) by collagenase digestion from three male patients with hereditary nephritis. The normal Goodpasture antigenicity of the 28 and 26 kD monomers and 54 and 50 kD dimers which may be isolated from the GBM was absent on one-dimensional immunoblots. Two-dimensional electrophoresis and immunoblotting studies showed absence of Goodpasture antigenicity of these molecular weight components as well as all cationic monomeric and dimeric spots. It is concluded that the expression of the Goodpasture antigen is altered in basement membranes of hereditary nephritis patients. The altered antigenicity thus acts as a marker for the underlying abnormality.

Anti-Glomerular Basement Membrane Disease↗
PubMed1989

Inherited defects of renal basement membranes.

For 15 to 20 years, electron microscopy studies have shown that some hereditary renal diseases are characterized by various abnormalities of the basement membranes. In the nail-patella syndrome, in Alport's syndrome and variants, and in benign familial hematuria, the changes involve the glomerular basement membrane (GBM). In nephronophthisis, the tubular basement membrane (TBM) is affected. These histopathologic features are not uniform. The progress afforded by biochemistry, immunology, and molecular biology allows us to compare these various lesions, to analyze their biochemical characteristics and their antigenicity, and to hypothesize as to the mechanisms involved.

Anemia↗
PubMed1989

Autoantibodies to glomerular antigens in patients with Wegener's granulomatosis.

Patients with Wegener's granulomatosis have autoantibodies to a neutrophil cytoplasmic antigen. As these patients often present with severe glomerulonephritis we investigated whether the same autoantigen was expressed in glomeruli by using both cultured human glomerular cells and frozen normal human kidney sections. Glomeruli were isolated from normal human kidney cortex by differential sieving and plated on to coverslips in growth medium containing various supplements. Cell types were identified by a series of markers and designated either epithelial, endothelial or mesangial. In single and double staining experiments, glomerular cells were incubated with a monoclonal antibody to the neutrophil cytoplasmic antigen (MCAW8), control mouse monoclonal IgG, sera from patients with Wegener's granulomatosis and control normal human serum. MCAW8 and Wegener's patient sera bound specifically to cultured epithelial and endothelial cells. MCAW8 was also found to bind to the glomerular epithelium in frozen sections. We conclude that autoantibodies to glomerular antigens are present in serum of patients with Wegener's granulomatosis and may be important in the pathogenesis of rapidly progressive glomerulonephritis.

Antibodies, Monoclonal↗
PubMed1989

Hereditary nephritis: immunoblotting studies of the glomerular basement membrane.

Hereditary nephritis (HN) is associated with antigenically abnormal glomerular basement membrane (GBM) manifest by reduced or absent binding of MCA-P1, a mouse monoclonal antibody which recognizes Goodpasture antigen. In the present studies, immunoblotting has been used to analyze antigenic and biochemical composition of renal tissue from patients with HN in whom binding of MCA-P1 could not be demonstrated by indirect immunofluorescence (IIF). Pooled normal collagenase-solubilized GBM (CS-GBM) and CS-GBM from three patients with either end-stage renal failure (ESK1-3) or HN (HNK1-3), were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis gel and, after transfer by Western blotting to nitrocellulose, reacted with sera from six patients with anti-GBM disease (GPS1-6) or anti-GBM antibody containing sera from three transplanted HN patients (HNS1-3), different from those patients with HN contributing HNK1-3. We found that GPS1-6 and HNS1-2 recognized the same six major bands in CS-GBM and ESK1-3 (between 54 and 24 kilodalton (kd) but only three bands (48, 42 and 24 kd) in HNK1-3. HNS3 only bound strongly to bands of 54 and 26 kd in CS-GBM or ESK1-3 and not all to HNK1-3. Immunoblotting studies of HNK1-3 have shown a partial rather than absolute loss of Goodpasture antigenicity (54, 28 and 26 kd bands). Studies with HNS1-3 suggest heterogeneity of antibody responses to allografted kidneys between patients with HN; HNS-3 showed restricted antibody specificity with recognition in CS-GBM of some bands antigenically absent from HN kidney. The abnormality in HN kidneys appears closely related to, but distinct from, the Goodpasture determinant and the inherited defect in HN may involve an essential modifying enzyme.

Autoantibodies↗
PubMed1989

Severe pulmonary hemorrhage and systemic vasculitis in association with circulating anti-neutrophil cytoplasm antibodies of IgM class only.

We report an association of severe pulmonary hemorrhage with circulating autoantibodies to neutrophil cytoplasmic antigens (ANCA) restricted to IgM class in three patients with systemic vasculitis. ANCA were detected by indirect immunofluorescence and isotype specific solid phase radioimmunoassay (SPRIA). Institution of immunosuppressive therapy was accompanied by an isotype switch to IgG ANCA and recovery in all three patients. In an associated study, ANCA activity was found in eluates from the washed glomeruli of two postmortem cases, with the same isotype distribution as was present in the sera.

Adolescent↗
PubMed1988

Antineutrophil cytoplasm antibody in crescentic glomerulonephritis.

Antineutrophil cytoplasm antibody (ANCA) has been reported in the sera of adults with Wegener's granulomatosis and microscopic polyarteritis, but this phenomenon has not so far been described in children. We report three children with crescentic glomerulonephritis in whom ANCA concentrations were raised at presentation. Two cases were idiopathic, and the other later developed features of Wegener's granulomatosis. In all three, plasma exchange and immunosuppression removed ANCA, but in only one case was there clinical improvement. This child later developed classical nasal lesions of Wegener's granulomatosis associated with a decline in renal function and a rise in ANCA. Plasma exchange and immunosuppression again produced a good clinical response and removed ANCA. This suggests that ANCA is either a marker of disease activity, or is involved in the pathogenesis of disease.

Autoantibodies↗
PubMed1987

Prospective study of radioimmunoassay for antibodies against neutrophil cytoplasm in diagnosis of systemic vasculitis.

The diagnosis and management of Wegener's granulomatosis and microscopic polyarteritis are complicated by the lack of specific diagnostic tests. The diagnostic performance of a solid-phase radioimmunoassay, which detects the autoantibodies against neutrophil cytoplasm present in these disorders, was assessed in a prospective study of patients with suspected vasculitis and/or rapidly progressive nephritis. The assay had a sensitivity and specificity of 96% when carried out in combination with a specific inhibition stage and indirect immunofluorescence staining of alcohol-fixed normal neutrophils.

Autoantibodies↗
PubMed1987

Association of alkaline phosphatase with an autoantigen recognised by circulating anti-neutrophil antibodies in systemic vasculitis.

A solid phase radioimmunoassay has been developed to detect circulating autoantibodies to neutrophil cytoplasmic antigens in systemic vasculitis. After fractionation of these antigens by size, with gel filtration high performance liquid chromatography, sera from patients with clinically different forms of systemic vasculitis, Wegener's granulomatosis (WG) and microscopic polyarteritis (MP), showed contrasting specificities of binding. WG sera bound to 100, 6.2, and 1.8 kD components, whereas MP sera bound only to the 100 kD component, allowing immunological distinction between the syndromes. The 100 kD component recognised by both WG and MP sera also showed alkaline phosphatase activity. Further evidence for this association was obtained by direct binding experiments between systemic vasculitis sera and calf-intestinal or human neutrophil alkaline phosphatase and by the cross-reactivity of W8, a monoclonal antibody raised to a neutrophil cytoplasmic autoantigen, with various preparations of the enzyme.

Alkaline Phosphatase↗
PubMed1987

Specific immunoabsorption.

Rapidly progressive glomerulonephritis occurs in patients developing autoantibodies to the glomerular basement membrane (GBM) and in multisystem vasculitic syndromes such as Wegener's granulomatosis (WG) and microscopic polyarteritis (MPA). In anti-GBM disease the pathogenicity of the autoantibodies has been established by transfer experiments; new solid-phase radioimmunoassays (RIAs) for circulating autoantibodies allow early diagnosis and effective monitoring of treatment. Sequential measurements of antibody levels showed that their generation is self-limiting (even without treatment) and that their production can be arrested more quickly with immunosuppressive therapy (cyclophosphamide and high dose steroids) together with intensive plasma exchange. In systemic vasculitis, no pathogenic agent has been identified and the diseases are rarely self-remitting. In WG, antibodies to cytoplasmic components of normal human neutrophils (and monocytes) were reported to be detectable by indirect immunofluorescence, with titres correlating with disease activity. We confirmed this and showed that antigen can be extracted from normal human neutrophils and used as ligand in a solid-phase RIA. Sera from patients with other forms of systemic vasculitis, such as MPA, as well as WG, are positive in this assay. The antigens have been further characterized by HPLC fractionation on a Toyosoda TSK gel filtration column. In WG, antibodies were directed towards cytoplasmic fractions of 100, 6 and 2 kDa; in MPA, antibody reacted only with the 100 kDa fraction. These findings suggest a humoral pathogenesis in these disorders and indicate that this approach may be helpful in the classification, diagnosis and monitoring of therapy in the systemic vasculitides. Further characterization of the autoantigen and its potential use in specific immunoabsorption are discussed.

Alkaline Phosphatase↗
PubMed1987

Variants of Alport's syndrome.

Variants of Alport's syndrome include mainly those associated with hereditary macrothrombocytopenia (and occasionally leukocyte inclusions) or with esophageal, tracheobronchial and genital leiomyomatosis. Within Alport's syndrome there appears to be no justification for differentiating those with nephritis and deafness from those with nephritis alone. However, in indirect immunofluorescence studies using the mouse monoclonal antibody, MCA-P1, which recognizes the glomerular basement membrane (GBM), reduced or absent binding was found in 20 of 42 cases of hereditary nephritis. Most of these showed typical ultrastructural GMB changes. These results suggest that there is probably a subset of patients characterized by typical GBM lesions and an absence, inaccessibility or abnormality of the GBM antigen recognized by MCA-P1.

Humans↗
PubMed1987

Factors affecting the glomerular protein leak after polyclonal activation in the HgCl2-induced model of anti-GBM disease in the brown Norway rat.

The administration of the polyclonal activator HgCl2 (1 mg/kg i.p.) to Brown Norway (BN) rats on days 0, 2, 4 and 7 resulted in the cyclical production of anti-glomerular basement membrane (GBM) antibodies, the first peak of which occurred at day 14 with a smaller peak at day 26. Glomerular anti-GBM antibody levels were also raised at day 14. Renal injury as measured by urinary loss of albumin and complement (C3) was also cyclical, being maximal on days 15 and 23-26. However, urinary protein excretion was significantly diminished on the days corresponding to the first peak of circulating antibody levels if peripheral monocyte counts were reduced by the repeated injection of anti-monocyte antiserum. Protein excretion was also reduced after the administration of anti-polymorphonuclear neutrophil (PMN) antiserum. Finally, glomerular protein excretion was independent of depletion of serum C3 levels to less than 10% of pooled normal sera by the repeated administration of Cobra Venom Factor (CVF) on days 9 and 11. These findings demonstrate that in the absence of progressive tissue injury in this model, glomerular protein excretion fluctuates according to circulating levels of anti-GBM antibody and that, despite being independent of complement, tissue injury may be increased in the presence of complement activation.

Animals↗
PubMed1987

Circulating T-cell populations during mercuric chloride-induced nephritis in the Brown Norway rat.

Fluorescence-activated cell sorter analysis was used to study the peripheral lymphocyte populations during mercuric chloride (HgCl2)-induced autoimmune nephritis in the Brown Norway (BN) rat. Sequential studies showed a transient loss of T cells from peripheral blood attributable to decreases in the percentage of T-helper cells. In addition, there was a decrease in the percentage of T-cytotoxic/suppressor cells prior to the appearance of circulating anti-GBM antibodies, followed by elevated levels of T-suppressor cells during down-regulation of the response. This method may allow closer inspection of the events linking changes in T-cell populations and induction and termination of an autoimmune response.

Animals↗
PubMed1987

A single autoantigen in Goodpasture's syndrome identified by a monoclonal antibody to human glomerular basement membrane.

A mouse monoclonal antibody (P1) to the autoantigenic component of human glomerular basement membrane (GBM) was used to study the immunochemistry and tissue distribution of the Goodpasture antigen and the specificity of the human autoimmune response in Goodpasture's syndrome (anti-GBM disease). In solid phase assays, monoclonal antibody P1 bound to collagenase-solubilized human GBM (the ligand used in assays for human autoantibody), but not to other biochemically defined components of basement membrane. On Western blotting, P1 bound to the same 6 bands in solubilized GBM (between 26 and 58 kilodaltons with major bands at 26 and 54 kilodaltons) that were recognized by sera from all 42 patients studied with anti-GBM disease. Preincubation with sera from 8/8 patients blocked the subsequent binding of P1 from 83 to 89% on densitometer scanning of the Western blot; and preincubation with P1 blocked the binding of sera from 6/6 patients from 58 to 89%. Indirect immunofluorescence and immunoperoxidase studies revealed that the pattern of binding of P1 was identical to that of antibody eluted from the kidneys of a patient with Goodpasture's syndrome; there was linear binding to GBM, Bowman's capsule, and distal tubular basement membrane. In addition, P1 bound to basement membranes in lung and choroid plexus, and to membranes of the lens capsule, choroid, and retina of the eye and cochlea, but not to other organs studied. It is concluded that there is a single major autoantigenic component of human GBM (the Goodpasture antigen), which is present on fragments of different molecular weight in the collagenase digest. This antigen is distributed throughout well-defined basement membranes known to be involved in both Goodpasture's and Alport's syndromes. Human anti-GBM antibodies bind to the same (or closely related) determinants which are recognized by P1, demonstrating that the autoimmune response in Goodpasture's syndrome is of highly restricted specificity.

Anti-Glomerular Basement Membrane Disease↗