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PubMed1983

Circulating IgA immune complexes in patients with psoriasis.

The sera of 21 patients with psoriasis were examined for the presence of IgA-containing circulating immune complexes (CIC) using the Raji IgA radioimmunoassay. In addition, the Raji IgG radioimmunoassay and 125I-Clq binding assay were used to detect IgG- and IgM-containing CIC. Twenty-five patients with other hyperkeratotic skin disorders were studied as controls. Patients were studied before institution of systemic therapy with etretinate (20 patients) or 13-cis-retinoic acid (1 patient). In addition, sera of 15 of the patients treated with etretinate were studied before, during, and after therapy. The extent of pretreatment disease involvement as well as response to therapy were evaluated in a blinded fashion. Fourteen of 21 (67%) patients with psoriasis had evidence of IgA-containing CIC at some time during the course of their disease, as compared to only 1 of 25 patients with other hyperkeratotic skin disorders. In contrast, only 2 of 19 (11%) had evidence of IgG-containing CIC using the Raji IgG assay, and only 1 of 19 (5%) had evidence of IgG- or IgM-containing CIC using the 125I-Clq binding assay. A positive correlation was found between the extent of pretreatment disease involvement and the level of IgA-containing CIC by linear regression analysis (p = 0.01). There was, however, no correlation between clinical improvement and the presence or level of IgA-containing CIC in 15 patients followed during therapy. Sucrose density gradient analysis of the IgA-containing CIC found in 2 of these patients demonstrated IgA-containing CIC in the 9S to 13S region. The finding of IgA-containing CIC in a significant number of patients with psoriasis and the relative absence of IgG- or IgM-containing CIC suggest that IgA-containing CIC may play a role in psoriasis. The lack of correlation with clinical improvement, however, suggests these IgA-containing CIC are not directly related to the cutaneous manifestations of psoriasis, but may be important in the modification of immune or inflammatory responses in these patients.

Adult↗
PubMed1988

New complement fixation test with peroxidase-labeled complement Clq for direct and quantitative determination of antibodies to herpes simplex virus.

An enzyme-labeled complement fixation (ELISA-CF) test for the direct and quantitative determination of complement fixing (CF) antibodies has been developed. This paper described the introduction of the ELISA-CF test that used peroxidase-labeled Clq component of complement to detect CF antibodies which had reacted with herpes simplex virus (HSV), as a virus model. Equal volumes of heat-inactivated serum and the peroxidase-labeled Clq (P*-Clq) were simultaneously added to wells of microplates which had been coated with HSV CF antigen or with cell control antigen. The enzymatic activities of P*-Clq bound to the immune complex were determined photometrically. The ELISA-CF test allows processing of serum specimens in a 3-hr operation, with procedural simplicity and increased specificity and sensitivity compared with the conventional CF test.

Antibodies, Viral↗
PubMed1982

Bullous pemphigoid: a correlative study of autoantibodies, circulating immune complexes and dermo-epidermal deposits.

Twenty bullous pemphigoid (BP) patients were studied to establish any correlation between free anti-basement membrane zone (BMZ) antibodies, circulating immune complexes (CIC) and dermo-epidermal junction deposits. CIC levels were evaluated by 2% polyethylene glycol (PEG) precipitation. The twenty patients were found to have IgG and/or C3 deposited in the BMZ. Eight of the twelve patients who had no free anti-BMZ antibodies displayed a positive in vivo C4 and/or CIq staining and high levels of CIC. Moreover, CIC were detected in only one patient with positive circulating free anti-BMZ antibodies. The presence of free anti-BMZ antibodies was generally found to correlate with the absence of cutaneous deposits of CIq and /or C4 and with negative CIC; on the other hand, the absence of free anti-BMZ antibodies was generally found to correlate with high levels of CIC and with deposits of C3 and CIq and/or C4. The absence of circulating free anti-BMZ antibodies in BP patients, could be explained by the formation of CIC. It is possible that BMZ antigens released from damaged tissue could combine with free antibodies and form complexes in the blood. The release could involve locally formed immune complexes. Elevated CIC levels were generally found to correlate with the presence of active disease.

Aged↗
PubMed1989

The lupus band test in oral mucosa, conjunctiva and skin.

The prevalence and clinical significance of subepithelial immunoglobulin and complement deposition (the lupus band) were examined in the uninvolved sun-protected skin of the forearm, the uninvolved sun-protected lip mucosa and sun-protected bulbar conjunctival mucosa in systemic lupus erythematosus (SLE) and chronic cutaneous lupus erythematosus (CCLE). In SLE, linear deposition of an immunoreactant at the BMZ was detected in 32% (6/19) of skin biopsies; 21% (4/19) of lip mucosal biopsies and 42% (5/12) of conjunctival biopsies. There was no significant difference in the sensitivity of the test at different sites in SLE and no correlation between a positive test in skin, lip or conjunctiva and clinical mucosal involvement. In CCLE, linear deposition of an immunoreactant at the BMZ was found in 3% (1/32) of skin biopsies; 3% (1/29) of lip mucosal biopsies and 50% (10/20) of conjunctiva and clinical mucosal involvement. In the conjunctiva, IgG was present in all but one of the biopsies and was the only immunoreactant in 90% (9/10) of positive CCLE biopsies and 60% (3/5) of positive SLE biopsies. In lupus erythematosus immunoreactants may be deposited in the basement membrane zone beneath non-keratinizing mucosal surfaces of the lip and the eye as well as the skin. In CCLE, the test may be positive in conjunctiva when skin and lip are negative.

Adolescent↗
PubMed1991

Characterization of anti-endothelial cell antibodies in systemic lupus erythematosus (SLE).

IgG anti-endothelial antibodies (AEA), as measured by ELISA or immunoblotting technique could be detected in serum samples of 56 out of 64 patients with SLE (88%) and mainly occurred in monomeric form. AEA were not cell specific, because the binding reactivity was absorbed partially by both fibroblasts and peripheral blood mononuclear cells. No correlation was found between the presence of AEA and anti-nuclear antibodies. Immunoblotting revealed reactivity of AEA against endothelial antigens ranging in size from 15 to 200 kD. AEA titres were significantly higher in patients with joint or skin abnormalities, compared with patients without these abnormalities. A significant correlation was found between nephritis in SLE and the presence of AEA reactivity against endothelial membrane antigens of 38, 41 and 150 kD. These data show that the pattern of AEA reactivity in serum of SLE patients is heterogeneous, and suggest that AEA against a limited number of antigens may be involved in the pathogenesis of nephritis in SLE.

Antibodies, Anti-Idiotypic↗
PubMed1991

Localization of 20-kD homologous restriction factor (HRF20) in diseased human glomeruli. An immunofluorescence study.

The 20-kD homologous restriction factor (HRF20), which is identical to CD59, is a membrane-associated protein which inhibits the reaction of C9 to form membrane attack complex (MAC) of homologous complements. In various human glomerular diseases deposition of complement components is frequently seen and MAC is reported to associate with immune deposits. Using a specific monoclonal antibody, 1F5, against HRF20, we attempted to study the localization of HRF20 in human glomerulonephritides and to compare the localization of HRF20 with those of immune deposits and MAC. The frozen sections of kidney specimens were fixed in acetone at room temperature before staining. In normal kidneys and kidney specimens from the patients with minimal change nephrotic syndrome, membranous nephropathy, and IgA nephropathy, HRF20 was strongly localized in the peritubular capillaries and along Bowman's capsules. A weaker but well-defined staining was obtained in the mesangial area and faint staining was seen along the glomerular capillary walls. In contrast, glomerular capillary walls were rather strongly stained in the cases with diffuse lupus nephritis which had subendothelial dense deposits. These data suggest that HRF20 (CD59) is present in the human glomeruli and its expression is enhanced under certain conditions such as lupus nephritis.

Antigens, Differentiation↗
PubMed1993

Studies on the mechanism of complement-mediated inhibition of antibody binding to HIV gp41.

We have previously demonstrated that HIV envelope gp41 binding to specific antibodies decreases after preincubation of fluid-phase gp41 in normal human serum. This inhibition is proven to be mediated by the classical complement pathway. In this study recombinant gp41 (rgp41) and/or synthetic peptides were preadsorbed to solid phase, and then complement (normal human serum/heated human serum/purified Clq/heated Clq) and anti-gp41 antibodies were added either after each other or simultaneously, and the amounts of bound antibody, and deposited C3b, C4b and Clq were measured. Complement-dependent inhibition of antibody binding to solid-phase rgp41 was found, and Clq seems to be at least partially responsible for this phenomenon. Heating of Clq did not affect this process. Higher amounts of anti-gp41 antibodies significantly and dose-dependently enhanced C4b and C3b fixation to solid-phase rgp41. In the case of synthetic peptides corresponding to the immunodominant region of gp41, significant antibody binding to the solid-phase peptides was also detected, and pretreatment of peptides preadsorbed to solid phase with normal human serum almost totally abolished the antibody binding.

Amino Acid Sequence↗
PubMed1982

Mercuric chloride induced autoimmune disease in Brown-Norway rats: sequential search for anti-basement membrane antibodies and circulating immune complexes.

Mercuric chloride induces in the Brown-Norway rat a biphasic autoimmune disease characterized initially by linear IgG deposits along the glomerular basement membrane followed later by granular IgG deposition. In the present study, anti-glomerular basement membrane antibodies and immune complex-like material were sequentially assessed in serial serum samples. Both were transiently found at the same period. Glomerular linear IgG deposits were present on day 11 but circulating anti-glomerular basement membrane antibodies were only found later on day 16. Circulating immune complexes were first detectable on day 8 before the earliest granular IgG deposits were first observed in the spleen vessels on day 16. The disappearance of circulating anti-glomerular basement membrane antibodies and of circulating immune complexes, although HgCl2 injections were pursued, is in agreement with the self-limited character of mercuric chloride induced autoimmune disease and suggests the induction of immunosuppressive mechanisms.

Animals↗
PubMed1984

Immunohistological differential diagnosis of inflammatory colonic diseases.

Immunohistological investigations were carried out on human colonic tissue from, I healthy mucosa, 2 slightly inflamed mucosa, 3 mucosa with ulcerative colitis, 4 mucosa with Crohn's colitis, using antibodies against immunoglobulins and complement components. All our antibodies, including F(ab')2 fragments, demonstrated a progressive increase of labelled cells from healthy mucosa through slightly inflamed mucosa to mucosa with ulcerative colitis, in contrast to a complete absence of labelled cells in cases of Crohn's disease. The results are discussed with regard to their pathogenesis and their clinical significance for the differentiation of ulcerative colitis and Crohn's colitis.

Colitis↗
PubMed1983

Antibody-independent binding and activation of complement by Schistosoma mansoni adult worms.

The in vitro binding serum complement (C) components to Schistosoma mansoni worms was studied. By exposing frozen sections of adult male and female parasites to normal human serum, binding of both classical and alternative pathway C components was observed. By immunofluorescence (IFL) microscopy selective binding of Clq, C4 and C3 to the schistosomal tegument, internal structures, the intestinal tract and eggs was seen. The C4 and C3 binding was completely abolished in the presence of 10 mM EDTA. EGTA also completely inhibited binding of C4 and most of the C3 binding. These results suggest that C binding to S. mansoni adult worms occurs mostly by the classical activation pathway. However, the partial Ca2+ independence of C3 binding and the demonstrated binding of the regulatory protein beta 1H suggests that worms are capable also of C3 binding by the alternative pathway. No C binding occurred to intact worms. Although some in vivo bound immunoglobulin appeared to be present occasionally at the parasite surface and in the gut, this material did not account for the demonstrated extensive C deposition upon incubation of frozen sections with normal human serum in vitro. Antibody independence of the observed classical pathway C binding was further indicated by binding of isolated Clq to the same structures capable of binding C components from serum.

Animals↗
PubMed1986

Serum and plasma fibronectin binds to complement reacted immune complexes primarily via Clq.

The binding of fibronectin to human Clq, C3b, and complement-reacted immune complexes (IC) was investigated by enzyme-linked immunosorbent assays. Microplates were coated with BSA followed by incubation with rabbit-anti-BSA IgG or F(ab')2 fragments of rabbit anti-BSA. Incubation of the solid phase with serum at 37 degrees C caused attachment of Clq and C3b. Addition of EDTA to the serum inhibited the binding of C3b, but not Clq, whereas substitution of the anti-BSA IgG on the solid phase with the F(ab')2 fragments abrogated the Clq, but not the C3b binding. Fibronectin binding was observed after incubation of the solid-phase IC with serum or plasma at conditions where Clq was also bound, whereas only minor amounts of fibronectin bound to the solid phase IC via C3b. Purified fibronectin showed a dose-dependent binding to solid-phase IC pretreated with Clq or fibronectin-depleted serum, confirming that the binding of fibronectin to IC largely occurred via Clq. Significantly smaller amounts of fibronectin were bound to solid-phase IC incubated with plasma instead of serum, despite the higher fibronectin concentration in plasma. This difference was found not to be due to a fibrinogen-fibronectin interaction in plasma. Binding of fibronectin to preformed fluid phase IC incubated with serum was demonstrated by SDS-PAGE analysis of PEG-precipitated IC.

Antigen-Antibody Complex↗
PubMed1991

Localization of circulating immune complexes from patients with rheumatoid arthritis in murine spleen germinal centres.

In previous studies we have demonstrated high levels of rheumatoid factor (RF) and large-size (greater than 22S) circulating immune complexes (CIC) in the serum of rheumatoid arthritis (RA) patients with extra-articular disease. These findings were paralleled by a concurrent increase in the level of RF-associated cross-reactive idiotypes (CRI) and an apparent diversification of the RF repertoire detected in the serum of the same patients. In the present study we examine the ability of CICs to activate the complement system in vivo, and its possible influence on expanding the RF repertoire in RA patients with extra-articular disease. Activation of complement by CICs is the key for germinal centre localization and long-term retention of such complexes on the surface of follicular dendritic cells (FDC), and so provides a source for the selection of cells with high affinity receptors for IgG and leads to the establishment of immunological memory. CICs containing different immunoglobulin isotypes and from different patients localized in mouse spleen germinal centres. However, intense localization was mainly seen for IgG-containing complexes from the serum of patients with large-size (greater than 22S) IgG-IgM RF complexes. The ability of these complexes to localize in mouse spleen germinal centres was related to activation of the complement system via the classical pathway in the patients' sera. Localization of IgG complexes was significantly (P less than 0.05) higher in sera from RA patients with extra-articular disease than those with articular disease alone. This study demonstrates the ability of large-size (greater than 22S) IgG-IgM RF complexes to activate complement, and suggests a possible role for such complexes in modulating the immune response to IgG in RA patients with extra-articular disease.

Animals↗
PubMed1983

S-sulfonation: a reversible chemical modification of human immunoglobulins permitting intravenous application. I. Physicochemical and binding properties of S-sulfonated and reconstituted IgG.

S-sulfonation represents a reversible chemical modification of disulfide bonds by which under the special conditions chosen only about 2.2 cystine units per IgG molecule are cleaved. Physicochemical and functional evidence for reconstitution is presented. Molecules reconstituted in vitro or in vivo regain, within a few hours, a reactivity (antigen binding, immunoprecipitation, Clq-mediated cross-linking of immune complexes) comparable to equimolar control preparations.

Animals↗
PubMed1984

Lupus nephritis. Clinicopathology and immunopathology of 80 biopsy cases.

The clinicopathology and immunopathology of 80 cases of lupus nephritis in a total of 1,187 biopsies were presented. Histologically, they consisted of 11 cases of mesangial lupus nephritis (13.8%), 51 cases of diffuse proliferative lupus nephritis (63.7%), and 18 cases of membranous lupus nephritis (22.5%). No cases of focal proliferative type, minimal changes or end-stage kidneys were included. Ten cases were male and they had no qualitative and quantitative differences with female ones in any respects. The microtubular structures were found in glomerular endothelial cells with a 70% frequency and in the interstitial endothelial cells with a 46% frequency. In the latter case, microtubular structures tended to be localized in the perinuclear space as well as in the endoplasmic reticulum. Spherical microparticles were found in 46% of all cases and the incidences were significantly higher in the membranous type. Organized deposits with straight parallel microfilaments were found only in a single case. Electron-dense deposits with fingerprint pattern were not seen. Immunohistochemically, various immunoglobulins, complement components, and fibrinogen were found deposited more frequently in diffuse proliferative lupus nephritis. IgG was the predominant immunoglobulin deposited in capillary loops in membranous types, and IgA in the mesangium in mesangial types. Extraglomerular deposition of immunoglobulins and complements were found in 26.3% of all cases.

Complement Activating Enzymes↗
PubMed1993

Morphologic variations of dense deposit disease: light and electron microscopic, immunohistochemical and clinical findings in 10 patients.

Twenty-one renal biopsy specimens obtained from 10 patients with dense deposit disease (DDD) were investigated using light microscopy, electron microscopy and immunohistochemistry. The patients included four females and six males aged 6 to 35 years (mean 16.1 years). A morphological diagnosis of DDD was made following the ultrastructural detection of continuous intramembranous dense deposits (CIMDD) in some capillary loops of at least one of the series of the repeated biopsies from each patient. With light microscopy, six patients showed membranoproliferative glomerulonephritis (MPGN). The other four patients showed diffuse proliferative glomerulonephritis (DPGN) with acute lesions showing intraglomerular neutrophilic infiltration, hump formation and endothelial swelling in three and minor glomerular abnormalities in one. Follow-up biopsies were obtained in six patients. Two patients progressed from DPGN to MPGN within 7 months, whereas three patients with MPGN showed morphologic improvement that featured increased capillary patency and regional disappearance of dense deposits along with the reduction of proteinuria. Dense deposit disease did not always feature typical amorphous and osmiophilic CIMDD spreading across the whole width of the lamina densa. This classical ultrastructural manifestation was mainly found in the patients with histologic non-MPGN and a linear peripheral pattern of complement component (C3) deposition. The MPGN patients with a granular peripheral pattern of C3 deposition also had CIMDD, but also additionally featured less dense subepithelial deposits superimposed on the CIMDD to produce an appearance simulating membranous transformation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗