Biomedical subjects

R N Maini

Publications and source records attributed to R N Maini.

At least 289 records · Page 16Linked to original sources

PubMed1983

Separation of two molecular species of the Sm antigen by affinity chromatography with murine monoclonal and human anti-nuclear autoantibodies.

Nuclear ribonuclear protein (nRNP) and Sm were extracted from a 30-60% ammonium sulphate fraction of rabbit thymus extract by affinity chromatography. Immunoadsorbent columns were prepared from IgG extracted from an anti-nRNP serum, an anti-Sm serum and two monoclonal autoantibodies derived from a MRL/lpr mouse. All four immunoadsorbents isolated both nRNP and Sm antigens indicating that they exist as the 'nRNP/Sm complex' A species of Sm which did not bind to the anti-nRNP column and which was subsequently purified with the anti-Sm column was termed 'free Sm'. The Sm in the complex and free Sm were immunologically identical on immunodiffusion and gave similar polypeptide bands on polyacrylamide gel electrophoresis. However, they differed in that complexed Sm was sensitive to heat and RNAase. These studies provide direct evidence of a physical association between the nRNP and Sm antigens and indicate an additional molecular species of Sm whose resistance to RNAase may be due to different associated RNA species.

Animals↗

PubMed1983

In vitro immunoglobulin synthesis by lymphocytes from patients with rheumatoid arthritis. I. Effect of monocyte depletion and demonstration of an increased proportion of lymphocytes forming rosettes with mouse erythrocytes.

We have investigated B cell function in nine patients with rheumatoid arthritis (RA) compared to sex and age matched controls in a pokeweed mitogen driven system. Levels of IgG and IgM synthesized in the supernatant were measured by a competition ELISA. We have found that cultured mononuclear cells from RA patients showed a defective Ig synthesis when depleted of monocytes. In contrast RA mononuclear cells not depleted of monocytes produced substantial levels of Ig after stimulation by the mitogen. The percentages of T and B lymphocytes in the peripheral blood of RA patients were normal; however, an increased number of lymphocytes formed rosettes with mouse erythrocytes indicating an abnormality in the B cell pool. These results demonstrate defective in vitro immunoglobulin synthesis by RA lymphocytes and show the importance of monocytes in this culture system.

Adult↗

PubMed1983

In vivo fate of 125I SS-B (La) injected into mice.

The fate of the radiolabelled soluble cellular antigen SS-B (La) was compared with that of other 125I-labelled proteins of known molecular weight (MW) and electrostatic charge, following i.v. injection into BALB/c mice. The plasma half-life of 125I-SS-B was 3 min, while that of 125I-bovine serum albumin (similar MW and electrostatic charge) was 270 min. 125I-heat-aggregated IgG (MW greater than 1 x 10(6)) and 125I-7S human IgG (MW 168,000) had plasma half-lives of 40 min and greater than 300 min, respectively. Liver and kidney showed preferential uptake of 125I-SS-B, followed by a rapid decrease in radioactivity. During this time low MW, trichloroacetic acid (TCA) soluble, material appeared in urine. This suggests a specific uptake mechanism followed by a catabolic phase. These studies demonstrate that normal mice remove 125I-SS-B rapidly from the circulation and then degrade it. This rapid antigen elimination may protect against the induction of potentially harmful autoantibody responses.

Animals↗

PubMed1982

B-lymphocyte subpopulation which forms rosettes with mouse erythrocytes increased in rheumatoid arthritis.

We studied the peripheral blood lymphocytes of 22 patients with rheumatoid arthritis (RA) for the presence of a subpopulation of cells which form rosettes with mouse erythrocytes. In normal subjects these cells have been characterised as immature B cells which are non-responsive to pokeweed mitogen. The mean percentage of mouse rosette-forming cells (MRFC) in the rheumatoid group was 13 +/- 10(mean +/- 2 SD), a significantly higher value than the control mean of 5% +/- 4% (P less than 0.001). The T- and B-cell percentages in the rheumatoid patients were normal. The ratio of MRFC: B cells derived from these results was 3:4 in RA and 1:4 in normal subjects. Pre-incubation of rheumatoid peripheral blood lymphocytes at 4 degrees C gave higher values of MRFC (19% +/- 10%) than pre-incubation at 37 degrees C (13% +/- 10%, P less than 0.02), but no such temperature effect was found in the control group. There was no correlation between MRFC and rheumatoid disease activity or the patients' drug regimens. We conclude that the threefold increase in mean MRFC in patients with rheumatoid arthritis indicates an abnormality in the circulating B-cell pool.

Animals↗

PubMed1982

Measurement of the complement C3 breakdown product C3d by rocket immunoelectrophoresis.

A method is described for quantitative measurement of C3d in plasma and synovial fluid by the use of rocket immunoelectrophoresis after fractionation of the samples with 22% polyethylene glycol. This method has the advantage over radial immunodiffusion of being more sensitive (detecting C3d down to 3 mg/l) whilst proving equally reproducible. Investigations indicate that the collection of blood samples in EDTA prevents in vitro activation of C3 even after storage for up to 6 h at room temperature and up to 12 weeks at -70 degrees C. Elevated levels of C3d were found in a proportion of SLE and RA plasma samples and in synovial fluids from patients with inflammatory synovitis. It is suggested that C3 conversion in vivo may be assessed by measurement of C3d by the technique described, and when used in conjunction with measurements of complement components and immune complexes, offers a means of investigating complement catabolism by the classical and alternative pathways.

Animals↗

PubMed1982

IgE and IgE-rheumatoid factors in circulating immune complexes in rheumatoid arthritis.

The sera of 21 patients with rheumatoid arthritis (RA), 11 patients with systemic lupus erythematosus (SLE), and 20 healthy subjects were analysed for the presence of IgE in immune complex fractions. These fractions were isolated by polyethylene glycol precipitation and gel filtration. Thirteen sera from RA patients contained IgE immune complexes (IC) and 11 of these were from patients with extra-articular manifestations. One SLE and none of the control sera contained such material. The serum IgE level did not correlate with IgE content of the IC fractions. Higher mean serum IgE levels were found in RA patients with extra-articular complications than in controls or RA patients with joint disease only, but the differences did not reach statistical significance. IgE anti-rabbit IgG (IgE rheumatoid factors) could be demonstrated in some IgE positive IC fractions. Antibodies to IgE, in 2 instances characterised as belonging to IgG class, were also found in ICs. This suggests the presence of anti IgE complexes. It is suggested that IgE, including some with rheumatoid factor activity, is contained in complexes which may be involved in some extra-articular manifestations of RA.

Antibodies, Anti-Idiotypic↗

PubMed1982

The complement fixing ability of putative circulating immune complexes in rheumatoid arthritis and its relationship to extra-articular disease.

The hypothesis that the pathogenicity of putative circulating immune complexes (CIC) in rheumatoid arthritis (RA) is related to their ability to fix complement was investigated. Three assays for CIC were employed; (a) the 125I C1q binding assay (C1q BA), (b) the C1q solid phase assay (C1q SP) and (c) the Raji cell assay (RCA). Evidence for hypercatabolism of complement was obtained by using a highly sensitive quantitative assay for C3d (a breakdown product of C3) by rocket immunoelectrophoresis. One hundred and fifty-two patients with classical or definite RA were studied; 54 had clinical evidence of extra-articular disease including vasculitis, nodules, scleritis, neuropathy and lung disease; 98 patients had clinical evidence of joint disease alone. Plasma levels of C3d were significantly elevated in the RA group as a whole 16.7 +/- 4.4 mg/l (mean +/- 1 s.d.) compared with 13.1 +/- 3.25 mg/l in a group of 55 normal controls (P less than 0.01). Elevated levels of C3d were found in 26% of all patients but occurred significantly more often in the extra-articular disease group (P less than 0.05). Fifty-four percent of patients had at least one positive assay for CIC although no individual assay was positive in more than 36% of the group as a whole. The prevalence of positive CIC was significantly greater in those patients with extra-articular disease than in those with joint disease alone (P less than 0.005). Of the total of 82 patients with putative CIC, 30 (37%) had a raised C3d level. The coincident finding of positive tests for CIC and an elevated C3d level was very significantly correlated with the presence of extra-articular disease (chi 2 = 12.7 P = 10(-3)). Whilst putative CIC are frequent in RA (54%) these findings in contrast to previous work, suggest that the majority are not associated with abnormal complement activation and may account for the relative infrequency of clinically detectable active extra-articular disease.

Adolescent↗

PubMed1981

Titers of antibodies to RANA in rheumatoid arthritis and normal sera. Relationship to Epstein-Barr virus infection.

The disease specificity of antibodies to rheumatoid arthritis nuclear antigen (RANA) was examined by comparing anti-RANA titers in sera from 100 patients with rheumatoid arthritis (RA) with sera from 93 healthy controls. Anti-RANA antibodies were found in 86% of the RA sera and 56% of the controls. The higher titers in the RA sera were unrelated to clinical features or to measurements of circulating immune complexes or rheumatoid factors. To study the relationship of these antibodies to previous Epstein-Barr virus (EBV) infection, antibodies to the EB virus capsid antigen (VCA) were examined and found in 94% of the RA sera and 97% of the adult controls. Four of the six RA sera without anti-VCA antibodies had detectable anti-RANA antibodies, so that we might suggest anti-RANA can arise in the absence of EBV infection. From absorption experiments with non-EBV transformed extracts, we inferred that high anti-RANA titers could be due to reactions with non-Epstein-Bar virus related nuclear antigens. These data cast doubt on current speculation about a possible pathogenic role for Epstein-Barr virus in this disease.

Adolescent↗

PubMed1981

Effect of histamine on the mitogenic response of human lymphocytes and its modification by cimetidine and levamisole.

The phytohaemagglutinin (PHA) mitogenic response of human blood lymphocytes demonstrated a dose-dependent inhibition by histamine (in the range 5 X 10(-7) M). Using suboptimal mitogenic doses of PHA the suppression was more pronounced. Stimulation using different doses of pokeweed mitogen (PWM) was not altered by histamine. Purified T cells and a lymphocyte population depleted of histamine-receptor-bearing cells were less sensitive to the histamine effect. In the supernatants of histamine-stimulated cultures, suppressor factor activity was found. Cimetidine could reverse the effect of histamine in a dose-dependent manner. Adding levamisole to the PHA cultures also produced some antihistaminic effect.

Cimetidine↗

PubMed1981

Measurement of immunoglobulin production by peripheral blood mononuclear cells in vitro using a solid-phase immunoradiometric assay.

A simple solid-phase immunoradiometric assay for IgG and IgM is described. Supernatants from lymphocyte cultures are incubated in microtitre plates which have been precoated with anti-IgG or anti-IgM. Subsequent binding of 125I-labelled anti-immunoglobulin is measured and IgG and IgM in supernatants are estimated from the standard curve constructed for each assay. The assay is specific for human IgG and IgM, is able to detect nanogram amounts and offers advantages over other techniques for evaluating in vitro lymphocyte function.

Antibody Formation↗

PubMed1981

The effect of IgG aggregate size and concentration on reactivity in immune complex assays.

The reactivity of heat-aggregated IgG of known size, in the Raji cell assay, the C1q binding assay and the C1q solid phase radioimmunoassay as a function of concentration, has been investigated. Marked differences were found in the way that the three assays behave when the IgG concentration and aggregate size are varied. These findings indicate the pitfalls in attempting to express the results of immune complex assays performed on biological fluids in terms of equivalent concentrations of aggregated IgG.

Antigen-Antibody Complex↗

PubMed1981

Antibodies to nuclear antigens in polymyositis: relationship to autoimmune 'overlap syndromes' and carcinoma.

Thirty-two patients with polymyositis were categorised into 4 groups: (1) 'pure' polymyositis, (2) dermatomyositis, (3) myositis associated with autoimmune 'overlap syndrome', and (4) those with associated malignancy. Serum from each patient was examined for a range of antinuclear antibodies. Seventeen patients had ANA detected by immunofluorescence, 18 patients had raised DNA binding (greater than 25 U/ml), of whom eight had levels greater than 50 U/ml (SI conversion: U/l = U/ml x 10(3)). Antibodies to soluble nuclear antigens were detected in 23 (72%) by 1 or more of 3 methods, and in all of these anti-RNP was the main antibody detected. Antibodies to other soluble antigens were also present in 6 sera. In 2 cases, both patients with SLE/myositis overlap, these were shown to be anti-Sm. The remaining 4 had antibodies to various protein components of the extracts, but it was not possible to demonstrate an antibody of diagnostic specificity for polymyositis. Furthermore, quantitation of anti-RNP and anti-DNA antibodies failed to define a distinct clinical entity or exclude malignant disease. High levels of anti-RNP antibodies showed an association with Raynaud's phenomenon, sclerodactyly, and pulmonary fibrosis and an inverse correlation with the rash of dermatomyositis, suggesting that this antibody may be of pathogenetic rather than diagnostic significance.

Antibodies, Antinuclear↗

PubMed1981

Interpretation of the Raji cell assay in sera containing anti-nuclear antibodies and immune complexes.

The Raji cell assay is regarded as a test for the detection and quantitation of immune complexes. It is frequently positive in sera from patients with SLE. We have demonstrated a relationship between Raji cell binding and antibodies to DNA and soluble cellular antigens. In five sera containing high titres of antibodies of known single specificity, most of the Raji cell binding occurred in the 7S IgG fraction where the majority of anti-nuclear antibody was also found. When each of these sera was incubated with its specific antigen, Raji cell binding increased. Subsequent fractionation showed that this binding was in the high molecular weight fraction (greater than 200,000 daltons) and that Raji cell binding and antibody activity were abolished in the 7S fraction. These data confirm that Raji cell bind immune complexes but also indicate that 7S anti-nuclear antibodies may interact directly with Raji cells by an unknown mechanism. Therefore, in sera of patients with anti-nuclear antibodies, binding to Raji cells does not necessarily imply the presence of immune complexes alone.

Antibodies, Antinuclear↗

PubMed1980

Evidence of Chlamydia trachomatis infection in sexually acquired reactive arthritis.

Thirty male patients with sexually acquired reactive arthritis (SARA) have been studied at the time of their initial presentation and thereafter. Chlamydia trachomatis was isolated from the urethral exudate of 9 (36.0%) of the 25 patients from whom urethral specimens were taken, and elevated titres of IgM antibody of C. trachomatis were detected in 11 (36.6%) of the 30 initial sera. Thirteen (43.3%) of the patients has a positive urethral culture and/or elevated titre of IgM antibody, and it is therefore suggested that 43.3% of these patients suffered an acute chlamydial infection at or near the time of the onset of their joint disease. The demonstration of 4-fold or greater rises and/or falls in IgM antibody titre (8 patients) and IgG antibody titre (6 patients) in a group of 15 men studied throughout the course of their disease strongly supports this conclusion. A positive urethral culture and/or raised titre of IgM serum antibody was also detected in 25 (50%) of 50 men with uncomplicated nongonococcal urethritis (NGU), suggesting that the prevalence of chlamydial infections in the 2 conditions is similar. Titres of IgG serum antibody to C. trachomatis were, however, significantly higher in patients with SARA than in those with NGU or other rheumatic diseases, and in healthy controls. The geometric mean titres (GMT) of IgG serum antibody in patients with SARA, NGU, rheumatoid arthritis, ankylosing spondylitis, systemic lupus erythematosus, and in healthy controls were 1:47.5, 1:8.6, 1:2.2, 1;2.2, 1:3.5, and 1:1.4, respectively. These findings suggest that an exaggerated antibody response to acute infection by C. trachomatis may be an important factor in the development of SARA in some but not all patients.

Antigens, Bacterial↗

PubMed1980

Antibodies to extractable nuclear antigens in rheumatoid arthritis: relationship to vasculitis and circulating immune complexes.

Antibodies to extractable nuclear antigens (ENA) were analysed in the sera of fifty-two patients with severe rheumatoid arthritis (RA) who were divided into two categories: twenty-five with arthritis only and twenty-seven with extra-articular disease. Using haemagglutination, counterimmunoelectropheresis (CIE) and double diffusion, antibodies to ENA were detected in three (12%) of the patients with arthritis only. In the group with extra-articular disease, antibodies were found in sixteen (59%) of the patients. In ten patients the antibodies reacted with an RNase and DNAse resistant, but trypsin sensitive protein component of ENA. These patients all had extraarticular disease with digital vasculitis being a particularly common feature. Their sera also contained circulating immune complexes detected by elevated cryoprecipitate protein levels associated with relatively low complement levels. It is suggested that antibodies to soluble proteins of nuclear origin may be markers of circulating immune complexes in extra-articular RA.

Adult↗

PubMed1979

Immunopathological mechanisms in rheumatoid arthritis at the dual interface of the synovial membrane: the joint cavity and the pannus.

The significance of immune responses is examined in relation to clinicopathological changes in the rheumatoid joint and the concept of a dual site of action is developed. In the joint cavity interaction between immune complexes and complement is central to the phenomena observed, which depend on the generation of chemotactic factors and the ingress of polymorphs. Other chemical mediators--e.g. prostaglandins and lymphokines--are envisaged as playing a secondary or augmentory role. At the pannus-cartilage (and bone) junction the possibility is considered that changes are due to activation of a variety of cell types which results in enzymatic degradation of collagen in cartilage, osteolastic activity in bone and prostaglandin-induced depletion of bone. The production of migration inhibition factors by rheumatoid membranes is examined and some evidence in support of their lymphokine nature is found by gel filtration; their role as cell activators is considered.

Antigen-Antibody Complex↗

PubMed1979

Synthesis of sulphated proteoglycans by rheumatoid and normal synovial tissue in culture.

Synthesis of sulphated proteoglycans by cell lines derived from explants of 7 rheumatoid and 9 normal specimens of synovial tissue, as well as by 7 lines of skin fibroblasts from non-rheumatoid patients, was examined. Cells of all 3 types were cultured as monolayers. They were then disaggregated and their capacity to synthesise proteoglycan estimated in cell suspensions by the incorporation of [35S]-sulphate into CPC-precipitable material during 2 hours of incubation. Cell suspensions incorporated somewhat more [35S]-sulphate than corresponding duplicate monolayers. Synovial cells from rheumatoid patients incorporated 2 to 3 times as much [35S]-sulphate as synovial cells from normals. Skin fibroblasts, however, incorporated less [35S]-sulphate than rheumatoid or normal synovial cells up to the fifth passage. Thereafter their incorporation gradually increased to overtake that of synovial cells. About one-half to one-third of the total [35S]-sulphate labelled material was closely associated with cells from synovial tissues and fibroblasts respectively.

Adolescent↗

PubMed1979

Clinical and radiological features of osteonecrosis in systemic lupus erythematosus.

Symptomatic osteonecrosis occurred in 8 out of 68 patients with systemic lupus erythematosus. Multiple joints were involved in 3 patients, and weight-bearing joints were most frequently affected. Osteonecrosis tended to occur early in the disease, and the patients had all received corticosteroids. Symptoms tended to occur when the disease had progressed from an active phase into one of clinical and serological quiescence. In weight-bearing joints classical radiological changes were often absent at the onset of symptoms.

Adolescent↗