The role of the c-ANCA antigen in the pathogenesis of Wegener's granulomatosis. A hypothesis based on both humoral and cellular mechanisms.
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Antibody Formation↗
Biomedical subjects
M R Daha
Publications and source records attributed to M R Daha.
Biosynthesis of complement factor H by human umbilical vein endothelial cells. Regulation by T cell growth factor and IFN-gamma.
The present studies were initiated to characterize a 150-kDa molecule with inhibitory activity for C3bBb formation, which is present in human umbilical vein endothelial cells (HUVEC). Therefore, human endothelial culture supernatants (HECS) were analyzed for the presence of human complement factor H by ELISA. It was found that H was present in HECS. An immunoblot analysis of affinity purified H from HECS showed that the size of HUVEC H was identical to that of plasma H. The mean production of H by HUVEC of first passage cultures was 40 ng/10(6) cells/day. The synthesis of HUVEC H was fully inhibitable by the addition of cycloheximide to the cultures, suggesting that H is de novo synthesized. Additional evidence for de novo synthesis was obtained by using biosynthetic labeling with [35S] methionine, immunoprecipitation, and SDS-PAGE. It was demonstrated that, indeed, HUVEC produce and secrete factor H. Two forms of the protein were identified, the 150-kDa form and also a 45-kDa form, both forms have been identified in plasma. The functional activity of HUVEC H is identical to that of plasma H. IFN-gamma induced enhanced synthesis of H by HUVEC, whereas it had no effect on C3 synthesis. Supernatant from stimulated PBMC, T cell growth factor, enhanced synthesis of both H and C3. The present studies indicate that H is produced by HU-VEC and that H may function as an inhibitor of complement activation at the endothelial cell level and, thereby, together with molecules like decay accelerating factor and membrane cofactor protein, may influence resistance of endothelial cells to complement mediated damage.
Binding, Competitive↗
Anti-endothelial cell antibodies in patients with rheumatoid vasculitis.
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Antibodies↗
Binding of human IgA1 and IgA1 fragments to jacalin.
Interaction of jacalin, an N-terminal galactose specific lectin, with human IgA1 and IgA1 fragments was investigated. IgA1 and all galactose containing fragments bound to jacalin-Sepharose, including Fab fragments containing only the galNac linked to serine-224 and Fc fragments containing four gal-galNac sequences. These data indicate that both the galNac and gal-galNac sequences can interact with jacalin. Jacalin precipitated IgA1 and the fragments F(abc)2, F(ab')2 and Fc in agar gel and from solutions. It also precipitated Fab' fragments in agar gel. Jacalin did not precipitate Fab fragments significantly. This suggests that, except for the single binding site on the Fab fragments containing the galNac linked to serine-224, jacalin itself also has a limited number of sites to interact with N-terminal galactose residues. ELISA studies revealed that intact IgA1 had a lower jacalin binding capacity than F(abc)2 fragments which lack CH3 domains, than F(ab')2 which lack the CH2 and CH3 domains, and than Fc fragments containing four gal-galNac sequences. This led to the conclusion that part of the galNac or gal-galNac sequences in intact IgA1 molecules are inaccessible to interaction with jacalin. Cleaving the C-terminal domains off may have induced a reorientation of the hinge region structure, including the orientation of the carbohydrate units.
Animals↗
Activation of complement by bovine respiratory syncytial virus-infected cells.
Because complement activation is probably involved in the pathogenesis of as well as in recovery from the disease induced by bovine respiratory syncytial virus (BRSV), we studied the activation of complement by BRSV-infected cells in vitro in a homologous system. Binding of C3 on the surface of infected cells was measured in a biotin-streptavidin amplified ELISA, and complement-mediated lysis was measured in a 51Cr release assay. Without antibody, infected cells activated and bound more C3 than uninfected cells. C3 activation that occurred in the absence of antibody was largely mediated by the classical pathway and induced lysis inefficiently. BRSV-specific antibody enhanced complement activation as measured by both C3 ELISA and cytotoxicity assay. In the presence of antibody, C3 activation was largely dependent on the alternative pathway and efficiently induced lysis. Both IgG1 and IgM antibodies enhanced C3 activation, but IgG2 and IgA did not enhance C3 activation in our experiments. Preincubating cells with IgA or IgG2 did not inhibit C3 activation enhanced by IgG1 or IgM. Murine monoclonal IgG1 antibodies against epitopes on the Fusion protein of the virus also enhanced C3 binding, but differed in their capacity to induce complement-mediated lysis.
Animals↗
Elevated production of polymeric and monomeric IgA1 by the bone marrow in IgA nephropathy.
In bone marrow cultures of 15 patients with primary IgA nephropathy we found significantly (P = 0.02) increased synthesis of both monomeric and polymeric IgA1 compared to 23 controls, by using high performance liquid chromatography (HPLC) fractionation of culture supernatants. The relative contribution of polymeric to total IgA1 produced was not different for the two groups. Two-color immunofluorescence studies of the percentage of bone marrow IgA1 plasma cells able to bind secretory component in vitro showed no difference between patients and controls. In the sera of patients with primary IgA nephropathy the relative contribution of IgA1 polymers to total IgA1 was also similar to controls. These results indicate that in IgA nephropathy, the increased IgA production in the bone marrow is restricted to the IgA1 subclass. The production of both monomeric and polymeric IgA1 is increased in patients during a quiescent phase of the disease.
Adult↗
Quantitative detection of class-specific rheumatoid factors using mouse monoclonal antibodies and the biotin/streptavidin enhancement system.
An enzyme-linked immunosorbent assay (ELISA) for the quantitative detection of rheumatoid factors (RF) was developed using mouse monoclonal antibodies against human IgG, IgA and IgM together with the biotin/streptavidin enhancement system. One hundred and eight patients with rheumatoid arthritis (RA) of whom 47 had a positive serum latex agglutination assay, 100 healthy controls and 95 diseased controls (25 systemic lupus erythematosus (SLE), 25 ankylosing spondylitis, 20 osteoarthritis and 25 bronchial asthma) were evaluated for the presence of IgG-, IgA- and IgM-RF by ELISA. Elevated levels of IgG-, IgA-, and IgM-RF could be demonstrated in respectively 94%, 91% and 98% of serum samples from RA patients with a positive latex test and in 72%, 69% and 8% of serum samples from RA patients with a negative latex test. In the latter patient group, increased levels of one or more RF isotypes could be detected in 82% of the patients. Except for the presence of IgG-RF in serum of 20% of the SLE patients, increased levels of RF isotypes were present in less than 5% of the diseased controls. Highly significant correlations were found between serum IgM-RF levels as detected by ELISA and those of the latex and the Rose-Waaler agglutination assays. Positive correlations were also found between the serum levels of the three RF isotypes investigated and between the levels of RF isotypes as measured in serum and synovial fluid of the same patient. Compared to agglutination assays, the ELISA for the quantitative detection of RF isotypes is a more reproducible and sensitive test which avoids some of the problems encountered in earlier ELISA methods.
Agglutination Tests↗
Donor-specific lysis of human kidney proximal tubular epithelial cells by renal allograft-infiltrating lymphocytes.
In the present study methods are described to obtain both graft infiltrating cells (GIC) of host origin and proximal tubular epithelial cells (PTEC) of donor origin simultaneously from biopsy material of renal allografts undergoing rejection. The identity of PTEC cultures was established using monoclonal antibodies. GIC were shown to exhibit T cell functional activity. These GIC were shown to lyse trypsinized PTEC as well as PTEC monolayers grown from the corresponding biopsy, and not PTEC isolated from biopsies obtained from other patients. Therefore the lytic activity appeared to be donor-specific. Major histocompatibility complex class I antigens were involved since donor PHA-blasts, a target population well known to express class I molecules, were lysed by GIC, and the anti-class I MoAb W6/32 blocked cytolytic activity of GIC against donor PHA-blasts and against donor PTEC. We thus established that donor-specific lysis of a defined population of kidney epithelial cells, namely PTEC, may occur. This model system, in which GIC and PTEC can be propagated from one biopsy specimen may be useful for further study of cell-cell interactions involved in allograft rejection.
Antibodies, Monoclonal↗
Direct induction of MHC class I, but not class II, expression on endothelial cells by cytomegalovirus infection.
MHC expression on endothelial cells after cytomegalovirus infection was investigated using double antibody radioimmunoassays and immunofluorescence flow cytometry. After CMV infection there was an increase in class I and beta 2 microglobulin expression. This increase corresponds to the percentage of cells that are infected with CMV. There was no evidence that the increased class I expression was due to soluble factors produced by the infected cells. Although CMV only affects approximately 10% of the endothelial cells, class I and beta 2 microglobulin expression on the cell population exceeds that induced by an optimal dose of alpha-interferon. Class II expression is not increased after CMV infection. However, when gamma-interferon was added to the medium after CMV infection a normal increase in class II expression was found, suggesting that CMV infection does not inhibit the gamma-interferon-induced expression of these molecules.
Cells, Cultured↗
Complement-mediated endothelial cell damage in immune complex vasculitis of the skin: ultrastructural localization of the membrane attack complex.
Activation of the complement system is an important element in our concept of the pathomechanism of immune complex (IC) vasculitis. Both deposition of IC and attraction of polymorphonuclear leukocytes (PMN) are effected by products of complement activation. Actual tissue damage, however, is believed to be caused by PMN penetrating the vessel wall. Our former finding that deposits of membrane attack complex of complement (MAC) are found predominantly in skin lesions of patients with IC vasculitis and not in perilesional skin, has raised the question whether the complement system itself (by way of the MAC) contributes to tissue damage. Our present study shows the ultrastructural localization of MAC in lesional and clinically uninvolved skin in two patients with a cutaneous IC vasculitis. Lesional skin deposits of MAC were found on endothelial cells (EC) of upper dermal vessels and on infiltrating PMN. Uninvolved skin deposits of MAC were found on some EC, but clearly to a lesser extent than on EC of the lesional skin. In the skin of two healthy controls MAC was only found sporadically on EC. Deposits of MAC on EC in the lesional skin were often associated with a typical form of local cell swelling. This local form of endothelial cell swelling was incidentally seen in vessels of clinically uninvolved skin, but not in the skin of the two controls. The association of the endothelial cell swelling with deposits of MAC suggests that the complement system can have a direct damaging effect on EC in IC vasculitis by the assembly of MAC on the endothelial cell membrane.
Aged↗
Studies on the sensitivity to complement-mediated lysis of erythrocytes (Inab phenotype) with a deficiency of DAF (decay accelerating factor).
No episodes of clinically significant in vivo haemolysis have been reported in individuals with a novel form of decay accelerating factor (DAF) deficiency (Inab phenotype), nor do functional in vitro assays for complement-mediated haemolysis show the extreme sensitivity to lysis characteristic of paroxysmal nocturnal haemoglobinuria (PNH) erythrocytes. DAF appears to be totally deficient in the Inab erythrocytes as judged by immunochemical and functional assays. Unlike PNH, the only other described DAF deficiency (where several other phosphatidylinositol (PI)-linked membrane proteins are also absent), the only protein lacking from Inab erythrocytes appears to be DAF. The Inab phenotype seems to be an inherited specific defect in DAF whereas PNH is an acquired defect in the mechanism of insertion of PI-linked proteins into cell membranes. These findings support the view that susceptibility of PNH erythrocytes to in vivo and in vitro complement-mediated haemolysis is not due simply to DAF deficiency but to either the combined lack of several membrane proteins or to deficiency of other regulatory proteins such as the membrane attack complex inhibitor/homologous restriction factor (MIP/HRF). The findings also raise questions as to the role of erythrocyte DAF.
CD55 Antigens↗
Diagnostic value of immunological investigations on sera of patients with glomerulonephritis.
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Antigen-Antibody Complex↗
Humoral immune response to influenza vaccination in patients with primary immunoglobulin A nephropathy. An analysis of isotype distribution and size of the influenza-specific antibodies.
Primary IgA nephropathy (IgAN) is characterized by mesangial deposits of IgA1, increased serum IgA1 levels, and circulating immune complexes containing predominantly IgA1. It has previously been found that patients with IgAN have a higher than normal IgA response to vaccination, but the IgA subclasses have not been studied. To investigate whether the IgA hyperresponsiveness is limited to the subclass IgA1, which is involved in the pathogenesis of IgAN, we compared the immune responses of 18 patients with 22 healthy controls after intramuscular vaccination with inactivated influenza virus. Antibody titers were significantly higher (P less than 0.0001) for the IgA1 subclass in patients versus controls, but not for the other isotypes. A substantial portion of the IgA and IgA1 antiinfluenza immune response comprised polymers in both patients and controls. There was no preferential response of polymers in patients. Patients produced significantly more monomeric IgA1 antibodies than controls. These results show that patients with IgAN have a hyperresponsiveness limited to the subclass IgA1 and mainly expressed by an excess of monomers.
Adult↗
Complete and partial deficiencies of complement factor D in a Dutch family.
A young man suffering from recurrent Neisseria infections was shown to lack detectable serum complement factor D hemolytic activity. Addition to the patient's serum of purified factor D to a final concentration of 1 microgram/ml resulted in full restoration of the activity of the alternative pathway. Using an enzyme-linked immunosorbent assay, it was shown that the patient's serum did not contain measurable amounts of factor D antigen either. The sister, the father, as well as the parents of the mother had factor D levels within the normal range, and the factor D level of the mother was decreased. The capacity of the patient's serum, at concentrations up to 5%, to promote phagocytosis of Escherichia coli by normal human granulocytes was low when compared to normal serum. Substitution of the patient's serum with purified factor D resulted in a full restoration of opsonic activity. This study describes the first complete deficiency of factor D, and demonstrates its possible relation to recurrent Neisseria infections.
Adult↗
Diminished clearance of soluble aggregates of human immunoglobulin G in patients with rheumatoid arthritis.
Investigation of the capacity of the mononuclear phagocyte system to remove immune complexes from the circulation was performed by the administration of 125I-labelled aggregates of human immunoglobulin G (AIgG) to patients with seropositive rheumatoid arthritis and healthy volunteers. It was found that the rate at which AIgG disappeared from the circulation was significantly prolonged in patients with RA, t1/2 61 +/- 49 min, versus 26 +/- 8 min in healthy volunteers (p less than 0.01). We were not able to establish a correlation between the t1/2 of AIgG and immune complex levels in the circulation, or between t1/2 and articular disease activity (Ritchie index). The sites of removal of AIgG from the circulation were analysed by determining radioactivity levels detectable over liver, spleen and heart. No correlation was found between t1/2 and liver/spleen uptake ratios. We have demonstrated that the removal of AIgG from the circulation of patients with RA is abnormal, though the biological significance of this finding remains to be determined.
Aged↗
The current status of neutrophil cytoplasmic antibodies.
Several studies in the past 10 years have demonstrated the occurrence of autoantibodies against cytoplasmic constituents in patients with vasculitis and glomerulonephritis. In this review the nomenclature of these antibodies is discussed and assays and clinical associations are summarized. Although the antigens involved are not completely identified, antibodies and T cells reactive with myeloid lysozomal enzymes may both play a significant role in pathogenesis.
Antibodies, Antineutrophil Cytoplasmic↗
Interleukin 1 and poly(rI).poly(rC) induce production of granulocyte CSF, macrophage CSF, and granulocyte-macrophage CSF by human endothelial cells.
Electrophoretically pure human interleukin 1 (IL-1) beta was found to stimulate human endothelial cells in monolayer culture to elaborate colony-stimulating activity (CSA). Supernatant fluids from cultures stimulated with increasing concentrations of IL-1 were found to stimulate colony formation of myeloid (CFU-GM), erythroid (BFU-E), and multipotent (CFU-GEMM) progenitor cells in a dose-dependent fashion. The effect on mixed colony formation, however, was less than on CFU-GM and BFU-E growth. Similar to IL-1, the double-stranded RNA polyriboinosinic-polyribocytidilic acid (poly[rI].poly[rC]) also stimulated release of CSA by endothelial cells in a dose-dependent manner. The kinetics of IL-1-induced CSA release as opposed to poly(rI).poly(rC)-induced release were found to be different, in that poly(rI).poly(rC)-induced CSA production occurred more slowly. An anti-IL-1 beta antiserum was able to completely neutralize the IL-1-induced CSA release, but had no effect on poly(rI).poly(rC)-dependent CSA production, indicating that the latter effect was mediated by other mechanisms than intermediate production of IL-1 beta. Using specific immunologic assays, IL-1- as well as poly(rI).poly(rC)-inducible production of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage CSF, and macrophage CSF was found. The release of CSF from endothelial cells in response to IL-1 may be a mechanism for stimulating production of neutrophils and mononuclear phagocytes, and for attracting and activating these cells at sites of inflammation.
Bone Marrow↗
Clearance kinetics and tissue distribution of aggregated human serum IgA in rats.
In the present study the clearance kinetics and tissue distribution of human polyclonal heat-aggregated serum IgA (AIgA) of different sizes in rats was studied after intravenous administration of 125I-AIgA. The 125I-AIgA of different sizes disappeared from the circulation in a biphasic manner with an initial rapid half-life (T1/2) and a second slower T1/2. The first T1/2 was related to the size of the 125I-AIgA: high molecular weight (MW) 125I-AIgA was cleared much faster than 125I-AIgA with a low MW. Relatively more degradation products were observed in blood when high MW 125I-AIgA were injected as compared to low MW 125I-AIgA. The AIgA were mainly taken up by the liver. Eight minutes after injection of high MW 125I-AIgA, 90% of the injected dose was found in the liver, whereas less than 2% was detected in the spleen. Very little activity was detectable in other organs, such as lungs, heart and kidneys. In the present study 1-3% of the injected 125I-AIgA were found in the bile. Analysis of this material revealed that low MW 125I-AIgA were transported more efficiently to the bile than high MW 125I-AIgA. To obtain more insight into the receptors involved in the clearance of 125I-AIgA, rats were pretreated with ovalbumin or asialofetuin. The clearance of 125I-AIgA of different sizes was inhibited when rats were pretreated with asialofetuin. Pretreatment with ovalbumin had no effect on the clearance rates of 125I-AIgA. These results suggest a role for carbohydrate receptors, which recognize glycoprotein-containing galactose terminal residues on Kupffer cells, in the clearance of 125I-AIgA.
Animals↗