[Fibronectin and other immunologic parameters in chronic polyarthritis]

In 20 patients with rheumatoid arthritis the plasma fibronectin concentrations were measured and correlated with the levels of C-reactive protein, alpha 1-antitrypsin, alpha 2-macroglobulin, fibrinogen, C3, C4 complement fractions and alpha 2-antiplasmin in serum respectively plasma. Patients with rheumatoid arthritis showed plasma fibronectin concentrations within reference levels. However, the concentrations of C-reactive protein, alpha 1-antitrypsin, alpha 2-antiplasmin, fibrinogen and C3-complement fraction were significantly higher in comparison to the healthy controls. The results indicate that fibronectin does not belong to the group of "acute phase proteins". Measurement of plasma fibronectin give no additional information about the activity of rheumatoid arthritis.

Some factors affecting the quantitation of rheumatoid factors by enzyme immunoassay

Some factors affecting the use of enzyme-labelled antibody to human IgM or enzyme-labelled human IgG for the detection and assay of IgM RFs by enzyme immunoassay have been investigated. IgM RF levels, obtained by standard radioimmunoassay techniques, showed a better agreement with those obtained with enzyme-labelled antibody than with enzyme-labelled human IgG. Immuno-adsorption studies using a sheep cell agglutination test (SCAT) confirmed a partial loss of antigenicity of the IgG molecules due to glutaraldehyde treatment, which increased with the length of time of exposure to glutaraldehyde.

[Use of the proteinase inhibitor alpha 2-macroglobulin in synovial fluids of arthritis of different origins and its relation to serologic parameters]

Collagen and proteoglycan are major constituents of the articular cartilage. In rheumatic disorders joint damage is attributed to the excessive action of proteoglycan degrading proteinases (P) and specific collagenases, which are released by connective tissue- and inflammatory cells in the synovial compartment. Collagenase is secreted in a latent form, which requires activation by a variety of serine-proteinases. Thus, several different proteinases are involved in pathogenesis of joint disease. alpha 2-macroglobulin was shown to be the major inhibitor of proteinases in complex biological fluids. To assess the utilization of alpha 2M by proteinases in synovial fluids (SF) from different arthritides we have employed a newly introduced solid phase immuno-sorbent assay, which allows concentration of alpha 2M and its proteinase-complexes from biological fluids. Most pronounced utilization of alpha 2M (up to 50% of total SF alpha 2M) was found in marked joint inflammation as judged from RF, immunocomplexes, C3 complement activation and acute phase reactants. Supported by animal experiments, which revealed that alpha 2M.P complexes but not native alpha 2M induce synovitis in rabbits after repeated intra-articular administration, it is suggested that pathophysiological rise of alpha 2M.P may impair cellular functions in inflammatory connective tissue, e.g. synovial tissue.

Rheumatoid factors and secondary immune responses in the mouse. I. Frequent occurrence of hybridomas secreting IgM anti-IgG1 autoantibodies after immunization with protein antigens

The involvement of rheumatoid factor (RF)-secreting cells in normal immune responses was examined by screening hybridomas derived from 129/Sv mice during primary and secondary immune responses against foreign proteins. No RF-secreting cells were detected during primary responses, but up to 10% of the total number of clones obtained during secondary responses produced IgM with anti-IgG activity. Like typical mouse RF, these anti-IgG autoantibodies had a strict isotypic specificity, mostly for IgG1, and a much stronger avidity for immune complexes than for native IgG. The selective activation of IgG1-specific RF during these secondary immune reactions was not due to fortuitous antigenic similarities between mouse IgG1 and the antigens used for immunization, nor did it result from the use of adjuvants for priming, or from contamination of antigen preparations with lipopolysaccharide. It is therefore concluded that, in the 129/Sv mouse, RF production during secondary immune responses is a physiological phenomenon.

Binding of isolated rheumatoid factors to histone proteins and basic polycations

A fluorimetric immunoassay has been used to assess reactivity of rheumatoid factor (RF) with both histone proteins and other basic polycations (poly-L-lysine, poly-L-ornithine, and protamine) bound to an immobilised tyrosine-glutamic acid polyanionic copolymer. Isolated RF preparations can bind to histone proteins in this assay, notably to H3 and H4 histones, and this activity was always masked in the original whole seropositive sera. Binding of isolated RF was often noted also to the other large-molecular-weight basic polycations.

Immunogenicity and effector functions of glutaraldehyde-treated rabbit and mouse immunoglobulin G

Rabbit and mouse IgG treated with glutaraldehyde (GA) were immunogenic in homologous species. Glutaraldehyde treatment induced in the IgG molecule two types of antigenic determinants. One of them was found on the monomeric fraction of GA-treated rabbit IgG (haptenic determinant) and the other on the polymeric fraction (structural determinant). The haptenic determinants were found also on monoaldehyde-treated rabbit IgG and GA-treated Fab and Fc fragments. It was demonstrated that rabbit and mouse antibodies are specific for GA-treated IgG and have species specificity. While GA treatment did not alter the antigen binding capacity of rabbit IgG antibody, its effector functions (except protein A binding) were much affected. Thus it was found that GA treatment enhances IgG ability to react with rheumatoid factor, reduces drastically its capacity to activate the complement system, abolishes the cytophilic properties of IgG and accelerates its catabolic rate. The possible blocking effect of GA on the amino acid residues (mainly Lys) situated in or very close to the effector sites of the IgG molecule is suggested.

Uric acid effects on in vitro models of rheumatoid inflammatory and autoimmune processes

A neutrophil monolayer system was used to study the effects of uric acid on neutrophil-aggregate interactions important in rheumatoid inflammation. No effect on immunoglobulin G aggregate phagocytosis was seen, but hyperuricaemic levels of uric acid were associated with an enhancement of phagocytosis-induced release of the azurophilic granular enzyme beta-glucuronidase. A trinitrophenyl-coupled mononuclear leucocyte rheumatoid factor plaque-forming assay was utilised to study uric acid effects on polyclonal activation of immunocompetent cells. Low levels of uric acid enhanced and high levels suppressed this system. Hyperuricaemia may enhance some aspects of rheumatoid inflammation, while uric acid may modulate an important component of rheumatoid autoimmunity.

Immune complex assays in rheumatic diseases

A wide variety of antigen-nonspecific immune complex assays have been developed in recent years for the detection and quantitation of immune complexes in pathologic fluids. These assays detect complexed antibody regardless of the antigen involved. Almost all of these assays use biologic reagents that may react with substances other than complexed antibody. In addition, the assays do not differentiate nonspecifically aggregated antibody from antigen-complexed antibody. Hence, these assays are not absolute tests for immune complexes. On the basis of studies using these assays, "immune complexes" have been detected in a large number of rheumatic diseases. While these findings have been of considerable investigative interest, thus far they have been of little practical clinical utility. The detection of immune complexes has not been shown to be essential in any clinical conditions but may be helpful in monitoring disease activity in systemic lupus erythematosus (SLE) and may provide useful diagnostic information in two rare syndromes, Lyme arthritis and SLE-related syndrome.

Nitrogen mustard in severe rheumatoid arthritis

The value of intravenous bolus therapy was investigated in patients with severe active rheumatoid arthritis. Nitrogen mustard was given in 3 intravenous bolus injections (0.1 mg/kg body weight) over 3-5 weeks. In a controlled study of 11 patients the actively treated ones (7 cases) showed greater improvement in all the clinical and laboratory variables measured than did the controls (4 cases). A prospective evaluation of this treatment in 22 patients over 6-18 months showed it had a persistent effect and was associated with clinically significant improvements in the assessments of disease activity. We consider bolus therapy with intravenous nitrogen mustard to be of value, but its use should be restricted to patients with severe rheumatoid arthritis during hospital admission, and it should be combined with other therapy.

Joint fluid leukocytosis of patient with rheumatoid arthritis Computer analysis of possible explanative factors

The relationship between joint fluid leukocytosis and some clinical and laboratory parameters (disease duration, ESR, maximal titres of rheumatoid factor and of antinuclear factors, blood leukocytosis and sex) was studied in 27 consecutive patients with seropositive rheumatoid arthritis. The concentration of leukocytes was significantly higher in the synovial fluid than in peripheral blood. Variations of joint fluid leukocytosis could, however, not be explained by disease duration, actual ESR, maximal rheumatoid factor or antinuclear factor titres, concentration of blood leukocytes, or sex. It is suggested that a possible correlation between joint fluid leukocytosis and the listed parameters of rheumatoid arthritis may be too complex for analysis by a linear multiple regression model in samples of the present size.

Characterization of classes of intrathecally synthesized antibodies by imprint immunofixation of electrophoretically separated sera and cerebrospinal fluids

The use of imprint immunofixation (IIF) method to identify IgG, IgA and IgM classes of microbial antibodies in electrophoretically separated sera and cerebrospinal fluids (CSF) is described. The method was applied to the analysis of intrathecal antibody responses in mumps meningitis, subacute sclerosing panencephalitis (SSPE), neurosyphilis and multiple sclerosis (MS). Intrathecally synthesized mumps virus-specific IgG, IgA and IgM antibodies were demonstrated in the CSF of patients with mumps meningitis. The intrathecally synthesized IgG and IgM antibodies displayed oligoclonal characteristics, while the IgA antibodies appeared to be mainly polyclonal. The intrathecal measles antibody responses in SSPE appeared to be confined to IgG antibodies. In neurosyphilis, the intrathecal treponemal antibody response was predominantly of the IgG class, but IgA antibodies were demonstrated in two of nine patients. Intrathecally synthesized IgG antibodies to measles and/or varicella-zoster viruses were demonstrated in 17 of 18 patients with MS; IgA or IgM antibodies to these viruses were not detected.

In situ immune complex formation in the mouse glomerulus: reactivity with human IgM rheumatoid factor and the effect on subsequent immune complex deposition

An in situ model of immune complex formation in the mouse was utilized to study the interaction of human IgM rheumatoid factor (RF) with glomerular bound immune complexes (IC). Prior intravenous injection of RF did not interfere with in situ IC formation, but reacted with complexes once formed. RF injected after formation of in situ IC was deposited in the same distribution as the complexes and was capable both in vivo and in vitro of acting as an immunoabsorbent and binding IC with the same antibody species as the in situ IC, but which had a different antigen component. The potential for this in situ immunoabsorbent activity of RF in the pathogenesis of the chronicity of the lesion in glomerulonephritis is discussed.

Secretion of IgM-rheumatoid factor and IgM by blood lymphocytes in rheumatoid arthritis

A direct plaque forming cell (PFC) assay for the detection of complement fixing IgM-rheumatoid factor (RF) secreting lymphocytes was evaluated. The specificity of the RF-PFC assay was demonstrated by the inhibitory action of exogenous human IgG. The sensitivity of the RF-PFC assay was similar to that of a reverse PFC assay detecting all cells secreting IgM (IgM-PFC). In blood from 75% of seropositive patients with rheumatoid arthritis (RA) RF-PFC were demonstrated, median value 6.8 (range: 0.4-1477) RF-PFC/10(6) mononuclear cells. Practically no RF-PFC were detected in seronegative RA patients and controls. Despite the fact that most IgM-RF undoubtedly is produced outside the blood, a positive correlation was found between the number of RF-PFC and the Waaler-Rose titer in serum. The number of circulating IgM secreting cells did not differ significantly between seropositive RA patients, seronegative RA patients and controls. Comparison of RF-PFC and IgM-PFC in seropositive patients revealed that in mean 7% of IgM-secreting cells in blood secrete IgM-RF.

A sensitive method for detecting cells coated with antibodies with human monoclonal rheumatoid factor produced in vitro

A human monoclonal rheumatoid factor (RF) produced in vitro by an Epstein-Barr virus immortalized cell line has been used to detect and quantitate antibodies specifically bound to cells. The RF is purified from cell culture supernatant by a simple procedure and then radiolabeled. In this assay, the binding of 125I-labeled RF to cells coated with specific antibodies is determined. This RF method detects very low titers of antibodies directed against specific cellular antigens and also minorities of antibody coated tumor cells in mixtures with identical non-coated cells. The advantages of this unique human monoclonal antibody are discussed.

Hyperviscosity syndrome in rheumatoid arthritis

The course of a patient with rheumatoid hyperviscosity syndrome is described. Manifestations of hyperviscosity included somnolence, circulatory overload, bleeding diathesis and dilated retinal veins. Serum hyperviscosity was associated with marked hypergammaglobulinemia, elevated IgM and IgG serum concentrations, and high titers of rheumatoid factor. High molecular weight IgG-IgM immune complexes shown in the serum were considered responsible for the increased viscosity. An unusual feature of the hyperviscosity, was spurious hyponatremia and a negative anion gap. Plasmapheresis rapidly controlled acute features of hyperviscosity, lowered gamma globulin concentrations and led to normal serum sodium and anion gap. Clinical improvement was maintained with moderate prednisone doses.

The effect of human IgM rheumatoid factor on renal glomerular immune complex deposition in passive serum sickness in the mouse

The results of experiments reported in this paper show that intravenously injected human IgM rheumatoid factor binds in vivo to immune complexes previously deposited in mouse glomerulus. Prior injection of human IgM rheumatoid factor does not interfere with glomerular deposition of passively administered immune complexes. Evidence is presented to show that rheumatoid factor once attached to glomerular bound immune complexes is able to act as an immunoabsorbent and to bind further circulating complexes.

Correlation in rheumatoid arthritis of concentrations of plasma C3d, serum rheumatoid factor, immune complexes and C-reactive protein with each other and with clinical features of disease activity

The concentrations of C3d in the plasma and of C-reactive protein (CRP), immune complexes and rheumatoid factor in the serum were measured in 99 patients with rheumatoid arthritis. Most patients had raised levels, the values of which correlated with disease activity assessed according to a newly described index based on multivariate analysis of subjective, semi-objective and objective features of the disease. There were also significant correlations between the values for plasma C3d and circulating immune complexes, immune complexes and rheumatoid factor, serum CRP and immune complexes, and serum CRP and plasma C3d. Measurement of plasma C3d provides a useful means of detecting in vivo complement activation, which may be involved in the pathogenesis of rheumatoid arthritis, but neither C3d levels nor any of the other variables correlated as closely with disease activity as did the serum CRP concentration.

Detection and partial characterization of immune complexes in patients with rheumatoid arthritis plus Sjogren's syndrome and with Sjogren's syndrome alone

In order to characterize the immune complexes detected in patients with Sjogren's syndrome (SS) and with rheumatoid arthritis (RA), the sera of 19 patients with SS alone and 11 with SS plus RA were examined. Elevated quantities of circulating immune complexes (CIC) were detected in 67% by the C1q-binding assay (C1q-BA), 73% by the C1q-solid phase (C1q-SP) assay, 43% by the monoclonal rheumatoid factor solid phase assay (mRF-SP) and 33% by the mRF-inhibition assay (MRF-Inh). Elevated concentrations of IgM RF were detected in 83% and of IgG RF in 73% of the sera by radioimmunoassay. Strong correlations existed between RF of the IgM and IgG classes and both the C1q-BA and the C1q-SP. Three lines of evidence indicated that RF were important components of the immune complexes detected by these radioimmunoassays. These results indicated that in those patients with RA plus SS, as well as those with SS alone, both IgM and IgG RF made substantial contributions to immune complexes detected both by C1q-BA and C1q-SP.

Circulating autoantibodies to IgD in rheumatic diseases

Most mature B lymphocytes possess IgD on their cell surface. Antibodies to IgD produce an adjuvant-like effect in many experimental systems. Employing sensitive class-specific radioimmunoassays, elevated concentrations of autoantibodies to IgD of the IgA, IgM, and IgG classes were detected in the sera of 55% of patients with adult onset rheumatoid arthritis (RA), of 45% with systemic lupus erythematosus (SLE), of 67% with mixed connective tissue disease syndrome (MCTD), and of only 8% of juvenile RA. Marked differences in the class of anti-IgD were noted. An elevated IgA anti-IgD was detected in 45% (p less than 0.01) of RA sera, 27% of SLE sera, and 58% (p less than 0.01) of MCTD sera. IgG anti-IgD was increased in only 26% of RA, 32% of SLE, and 8% of MCTD sera. IgM anti-IgD was elevated in only one patient. IgA anti-IgD was inhibited greater than 90% by IgD but not at all by IgG. Correlations between the concentration of immunoglobulin G and IgA anti-IgD were noted in RA (rs = 0.37, p = 0.02), SLE (rs = 0.46, p = 0.015), and MCTD (rs = 0.4). These data suggest a potential role for autoantibodies to cell surface IgD as modulators of the immune system in some patients with autoimmune disorders.

Serum IgG and IgM rheumatoid factors by solid phase radioimmunoassay. A comparison between adult and juvenile rheumatoid arthritis

In this report, solid phase radioimmunoassays that specifically measure IgG rheumatoid factor (RF) and IgM RF in absolute concentrations are described. Polyclonal RF preparations were utilized as standards, and as little as 40 ng/ml of IgG RF and I ng/ml of IgM RF were detected. The IgG RF concentration of 26 seropositive rheumatoid sera was 439 +/ 755 micrograms/ml (mean +/- 1 SD), a level 107 times that of normal controls (P less than 0.001). In contrast, levels for 49 children with juvenile rheumatoid arthritis (JRA) were 6.1 +/- 3.7 micrograms/ml for those with a polyarticular onset (JRA-Po), and 27.3 +/- 113 micrograms/ml for the pauciarticular group (JRA-Pa), and 12.6 +/- 20.7 micrograms/ml for the group with a systemic onset (JRA-S). None of these values differed significantly from the value of 6.0 +/- 3.9 micrograms/ml measured in a juvenile control group. The IgM RF level in adult rheumatoid arthritis (RA) of 175 +/- 221 micrograms/ml was also significantly elevated compared to controls (P less than 0.001). In JRA, however, mean levels of 1.4 +/- 2.0 micrograms/ml (JRA-Po), 2.8 +/- 8.3 micrograms/ml (JRA-Pa), and 1.1 +/- 0.7 micrograms /ml (JRA-S) were not elevated significantly above the value of 1.2 +/-1.2 micrograms/ml measured in the juvenile control group. Hidden IgM RF was not found in 9 JRA sera tested. These marked differences in RF levels provide another indication that adult RA and JRA are distinct diseases.

Action of D-penicillamine on immunocomplexes containing rheumatoid factor

The affinity between purified rheumatoid factors (RF) and native or heat aggregated human IgG has been studied in vitro by polarization fluorescence in the presence and in the absence of D-penicillamine. The value of the dissociation constant was the same using native and heat aggregated IgG suggesting that binding to the aggregated protein is not dependent on the exposure of a new determinant lacking in the native molecule. The results obtained in the presence of D-penicillamine suggest that the concentration of the drug necessary to get a pronounced effect on the apparent dissociation constant of the immunocomplex between IgG and RF is not reached in vivo, in clinical situations.

A solid-phase assay for circulating immune complexes using monoclonal rheumatoid factors and peroxidase-linked protein A

A solid-phase monoclonal rheumatoid factor (mRF) assay for circulating immune complexes (IC) is described. Microtiter plates are coated with mRF, serum diluted 1 : 40 is added, and complexed IgG is detected with protein A coupled to peroxidase. Selective binding was obtained with aggregated human gamma-globulin and soluble IC prepared in vitro. Sucrose density gradient ultracentrifugation studies indicate that mRF binds intermediate-size IC (between 7S and 19S). Abnormal levels of IC were found in 78% of sera from patients with rheumatoid arthritis, 67% with systemic lupus erythematosus, and 87% with subacute bacterial endocarditis.

A comparative analysis of human IgM rheumatoid factor degradation by purified elastase and total granule extracts from human polymorphonuclear leukocytes

A modified digestion system using radiolabeled IgM rheumatoid factors (RF) and unlabeled IgG was used to examine IgM RF digestion by human polymorphonuclear leukocyte (PMN) elastase. Upon molecular sieve chromatography, the radioactive fragments coelute with fragments produced by elastase digestion of an IgM protein giving no RF activity. The fragments represent an Fab2-like fragment, an Fab-like fragment, and small peptides. Utilizing this same system, digests were performed at both acid and neutral pH to compare the proteolytic action of purified elastase on IgM RF (Ove) to the action of the total granule extract (TGE) from human PMN. At pH 4.5, purified elastase exhibits low-level protease activity, producing a slightly degraded IgM fragment with a molecular weight of about 800,000 daltons. In contrast, TGE at pH 4.5 completely degrades IgM RF to small peptides. At pH 7.5, the fragments produced by TGE digestion of IgM (Ove) coelute with fragments produced by elastase digestion under the same conditions. Thus elastase appears to be the major granule protease active in IgM RF degradation at the pH characterizing the inflammatory site.

[Interactions between rheumatoid factors and antinuclear autoantibodies: their occurrence in a concealed state in rheumatoid disease (arthritis); effect of D-penicillamine]

In this paper it is demonstrated that IgM rheumatoid factor (RF) can inhibit the detection of antinuclear antibodies (ANA) by the classical rat liver cryostat section method. This "inhibition" of IgG-ANA by IgM-RF may be due to the formation of high molecular weight complexes. It would be the same in vivo. This masking effect can explain interesting similarities and dissimilarities observed in the clinico-immunological profiles of rheumatoid arthritis and systemic lupus erythematosus. D-Penicillamine can restore ANA activity by dissociating ANA-RF complexes. A new technique is described for the detection of these masked ANA.

The association of cryoglobulinaemia with nodules, vasculitis and fibrosing alveolitis in rheumatoid arthritis and their relationship to serum C1q binding activity and rheumatoid factor

Two measurements of serum immune complexes, cryoglobulinaemia and 125I-C1q binding, have been performed in patients with severe rheumatoid arthritis (RA) and compared with normal levels. Cryoglobulinaemia was present in 20 out of 28 patients (71%) with extra-articular disease (mean level 17 micrograms/ml) including nodules, digital vasculitis, cutaneous ulcers, rash, neuropathy, lung disease and scleritis, but in none of 32 patients with joint disease alone (uncomplicated RA) (mean level 3 micrograms/ml). Cryoglobulinaemia correlates with, but probably does not antedate, extra-articular disease, and may be useful in predicting morbidity and mortailty in this group of patients. In contrast, serum 125I-Clq binding was raised in patients with uncomplicated RA and those with extra-articular disease, although levels were higher in the latter group. Both tests showed a negative correlation with serum haemolytic complement and a positive correlation with IgM rheumatoid factor although there were some sera with raised levels of rheumatoid factor without cryoglobulinaemia. These results suggest that cryoglobulinaemia is a better test than Clq-binding for demonstrating the presence of circulating immune complexes involved in the pathogenesis of extra-articular lesions.

Quantitation of rheumatoid factor activity by nephelometry

Rheumatoid factor activity can be quantitated by use of nephelometric assay system. The data presented show a good correlation between this new method and the older quantitative latex tube rheumatoid factor test. In addition, the nephelometric and latex tube testing of sera from normal, rheumatoid and non-rheumatoid patients yielded similar results, suggesting the two procedures share a similar immunologic specificity. The new nephelometric test for rheumatoid factor is simple to perform, endpoints are objectively determined, and test data are highly reproducible.

Vasculitis and Sjögren's syndrome with IgA-IgG cryoglobulinemia terminating in immunoblastic sarcoma

Generalized lymphadenopathy and other manifestations of Sjögren's syndrome developed in a 68 year old woman with a long history of systemic vasculitis and arthralgia. An unusual immunologic feature was hypogammaglobulinemia and immunoglobulin A (IgA) monoclonal immunoglobulinemia with mixed IgA-IgG cryoglobulin. At autopsy, the histopathologic findings were compatible with immunoblastic sarcoma. The monoclonal IgA protein, found in serum, pleural and pericardial fluids, showed rheumatoid factor activity. Immunocytes from the immunoblastic sarcoma were found to be the source of the monoclonal IgA protein.

Circulating immune complexes in Lyme arthritis. Detection by the 125I-C1q binding, C1q solid phase, and Raji cell assays

We have found immunoglobulin (Ig) G-containing material consistent with immune complexes in the sera of patients with Lyme arthritis. It was detected in 29 of 55 sera (55%) from 31 patients by at least one of three assays: (125)I-C1q binding, C1q solid phase, or Raji cell. The presence of reactive material correlated with clinical aspects of disease activity; it was found early in the illness, was most prominent in sera from the sickest patients, was infrequent during remissions, and often fluctuated in parallel with changes in clinical status. The results in the two C1q assays showed a strong positive correlation (P<0.001). They were each elevated in 45% of the sera and were usually concordant (85%). In contrast, the Raji cell assay was less frequently positive and often discordant with the C1q assays. In sucrose density gradients, putative circulating immune complexes sedimented near 19S; they, too, were detected best by the two assays based on C1q binding. An additional 7S component was found in some sera by the (125)I-C1q binding assay. Serum complement was often above the range of normal in patients with mild disease and normal in patients with severe disease but did not correlate significantly with levels of circulating immune complexes. IgM and IgG rheumatoid factors were not detectable. These findings support a role for immune complexes in the pathogenesis of Lyme arthritis. Their measurement, by either the (125)I-C1q binding assay or by the C1q solid phase assay, often provides a sensitive index of disease activity. Moreover, the complexes are likely sources of disease-related antigens for further study of this new disorder.

A simple radiolabelled rheumatoid factor binding assay for the measurement of circulating immune complexes

A simple assay for circulating immune complexes has been developed and the optimal conditions for reaction defined. Partially purified radiolabelled polyclonal or monoclonal rheumatoid factor was incubated with aggregated IgG or soluble immune complexes and the resultant macromolecule precipitated with 3% polyethylene glycol. Monoclonal rheumatoid factor was much the better reagent, allowing the detection of approx. 0.35microgram/ml or more of aggregated IgG. Soluble immune complexes formed in vitro at between x2--x20 antigen excess were detectable over a wide range of molecular size. Clinical studies indicated that the assay is a useful addition to the currently available techniques for measuring circulating immune complexes.

[Modifications in alpha 2 globulins, gamma globulins and in rheumatoid factor during gold salt therapy in rheumatoid arthritis]

A total dose of g 1.071, given as hydrosoluble salts for a 12 month period, showed a significant decrease in serum gamma globulins along with clinical improvement in 17 patients affected with rheumatoid arthritis. A decrease in alpha 2 globulins and in rheumatoid factor titre was observed too, but it was not significant. The data suggest that in rheumatoid arthritis the gold therapy might also be effective on the immunological disease mechanism.

IgM-class rheumatoid factor interference in the solid-phase radioimmunoassay of rubella-specific IgM antibodies

The interference of IgM-class rheumatoid factor (RF) in the solid-phase radioimmunoassay (RIA) of rubella virus IgM antibodies was studied. Acute rubella infections did not significantly activate RF. False-positive rubella antibody results were obtained, however, when patients with raised RF levels were tested. If a low rubella IgG antibody titre was present, a high level of RF was required to cause a false-positive IgM result; conversely, in sera with high IgG titres, only a low level of RF was required for interference. Although the false-positive IgM titres obtained were generally low, thet did show a positive correlation to both RF levels and rubella IgG titres. False-positive results were successfully avoided by removing the RF by absorption with heat-aggregated human gamma globulin. The absorption procedure did not affect true rubella IgM antibody titres.

Anti-fab' antibodies in human sera. II. A study of their possible association with C-reactive protein, rheumatoid and anticomplementary factors

The present study was undertaken to determine whether a relationship could be found between Fab' antibodies and the occurrence of C-reactive protein, rheumatoid and anticomplementary factors in the serum of patients with malignancies and other illnesses. The findings argue against the possibility that Fab' antibody activity is associated with a single disease entity. The very frequent occurrence of Fab' antibodies in hospital patients as opposed to healthy blood donors implies that their function is probably indirectly related to other immunological events. There is evidence to suggest that Fab' antibodies may serve as a mechanism for clearing immune complexes.

Radioimmunoassay of IgG and IgM rheumatoid factors reacting with human IgG

Although IgG rheumatoid factor may play a central role in the pathogenesis of rheumatoid arthritis, previously there have been no precise methods for its specific measurement in serum and synovial fluid. This paper describes a solid phase radioimmunoassay for the independent quantification of IgM and IgG rheumatoid factor reacting with the Fc fragment of human IgG. As measured by this assay, serum IgG rheumatoid factor levels differed significantly between patients with seropositive and seronegative rheumatoid arthritis and normal control subjects. In addition, several sera and joint fluids from patients with seropositive rheumatoid arthritis, even without vasculitis, were shown by gel chromatography to have acid-dissociable complexes of IgG rheumatoid factor suggestive of IgG-IgG dimer or trimer formation.

Rheumatoid factor-producing cells detected by direct hemolytic plaque assay

Lymphocytes secreting anti-IgC antibodies, rheumatoid factors (RF), can be detected in the peripheral bloods, synovial fluids, and bone marrows of patients with seropositive rheumatoid arthritis by using a direct plaque-forming cell (PFC) assay with sheep erythrocytes sensitized with reduced and alkylated rabbit IgG hemolysin. The autospecific nature of the RF produced by RF-PFC was indicated by inhibition studies in which the order of patency was human IgG greater than rabbit IgG greater than bovine IgG. In metabolic studies puromycin, cycloheximide, and venblastine suppressed RF-PFC. Cyclic AMP and cyclic GMP were without effect. A need was recognized for using full tissue culture media during the cell separation and plaquing procedures to optimize detection of the RF-PFC. RF-PFC may appear in the blood of patients intermittently despite their continuing presence in the bone marrow. They have been found in the peripheral blood, especially during acutely exacerbating polyarticular synovitis, generalized vasculities, or generally active, aggressive disease. RF-PFC were found in synovial effusions of new or recrduescent acute synovitis. RF-PFC were observed to disappear from the peripheral circulation and the bone marrow during therapy with cytotoxic drugs. The data are consistent with the hypothesis that the appearance of RF-PFC in the peripheral blood represents an anamnestic response to transiently appearing antigen. The nature of the antigen is not specified. The bone marrow may be a site of origin of RF-PFC.

Immunologic mechanisms in systemic vasculitis

Thirty-four patients with systemic vasculitis were studied to determine the possible type and frequency of associated immunologic abnormalities. The patients were divided into three clinical groups--those with systemic vasculitis without respiratory tract involvement, those with systemic vasculitis with respiratory tract involvement (particularly Churg-Strauss vasculitis and Wegener's granulomatosis), and those with limited vasculitis without visceral involvement. A diminished level of serum complement was found in half the patients with systemic vasculitis without respiratory tract involvement. These patients usually had diffuse skin disease that often was associated with the presence of rheumatoid factor and cryoglobulinemia and most likely represented an immune-complex induced disease. The serum IgE often was elevated in patients who had systemic vasculitis with respiratory tract involvement, particularly those with Churg-Strauss vasculitis and Wegener's granulomatosis, and may be a clue to the pathogenesis in this group of patients.

Serum immunoglobulins, rheumatoid factor, and pneumoconiosis in coal miners with rheumatoid arthritis

The occurrence and severity of pneumoconiosis were studied in 100 coal miners with rheumatoid arthritis (RA) and compared to findings in a geographically relevant survey of coal workers' pneumoconiosis. Contrary to European reports, miners with RA were not found to have an excessive frequency or severity of pneumoconiosis. In 55 of these men, serum immunoglobulin levels and rheumatoid factor were compared with data from matched RA patients with no history of silica exposure. The immunochemical results were unrelated to the stage of pneumoconiosis, nor did they differ from those in the control group.

Shunt nephritis: the nature of the serum cryoglobulins and their relation to the complement profile

The serum complement profiles of four patients with shunt nephritis indicated classical pathway activation of the complement system. The presence of mixed cryoglobulins was correlated with disease activity and the cryoglobulins were shown to be complement reactive. Antisera to two of the cryoglobulins recognized antigens of the infecting organism, and a specific bacterial antibody was identified in one cryoglobulin, giveing evidence that the cryoglobulins contained immune complexes. Bacterial antibody without detectable antigen was demonstrable in the sera indicating antibody excess. Renal morphology demonstrated mesangial proliferation and interposition with subendothelial and mesangial deposits. Parallels are drawn with active lupus nephritis.

Isolation of C1q-binding immune complexes by affinity chromatography and desorption with a diaminoalkyl compound

The applicability of affinity chromatography to the isolation of C1q-binding immune complexes (IC) in sera was explored. Purified human C1q was covalently coupled to agarose or adsorbed to IgG-agarose resins. Sera containing preformed virus-antibody complexes or rheumatoid arthritis (RA) sera were passed through the columns and C1q-bound IC, eluted off with 1,4-diaminobutan at mild basic conditions, were analysed by immunodiffusion, crossed immunoelectrophoresis, gel filtration and electron microscopy. Under conditions of antibody treatment which caused almost 100% inhibition of virus plaque formation, about 30% of formed 14C-labelled equine arteritis virus-antibody complexes was bound specifically to and desorbed from C1q-IgG agarose columns. Studies with RA-sera indicated the presence of both IgM-IgI and intermediate size IgG, C1q-binding, complexes in 3 out of 5 tested seropositive sera. In two sera only intermediate size IC were demonstrable. The results obtained in these two IC model systems suggested that the described methods could be useful for isolation of C1q-binding IC in general.

Vitamin B6 levels in rheumatoid arthritis: effect of treatment

Patients with rheumatoid arthritis were found to have low plasma pyridoxal phosphate. Treatment with 50-150 mg/day of pyridoxine hydrochloride for 3 months caused a rise in pyridoxal phosphate in most cases to more than 3 times pretreatment levels. There was, however, no improvement in the clinical aspects of rheumatoid arthritis.

Immune complexes in sera and synovial fluids of patients with rheumatoid arthritis. Radioimmunoassay with monocylonal rheumatoid factor

Evidence for the presence of immune complexes in blood, synovial fluid, and tisues of patients with rheumatoid arthritis (RA) includes low complement levels in blood and effusions, deposition of immunoreactants in tissues and vessel walls, precipitate formation after addition of monoclonal rheumatoid factor (mRF) to serum or synovial fluid. To quantitate immune complex-like material in RA patients, we developed a radioimmunoassay based on inhibition by test samples of the interaction of (125I)aggregated IgG (agg IgG) and mRF coupled to cellulose. This method could measure immune complexes of human antibody with hemocyanine prepared in vitro. The assay was not influenced by presence of polyclonal RF in test samples, nor by freezing and thawing. Normal levels of immune complex-like material in serum were less than 25 mug agg IgG EQ/ML. 12 of 51 RA sera examined (26%) contained more than 25 mug/ml. The presence of this material in RA sera was found to correlate with severity of disease, as measured by anatomical stage and functional class. There was an inverse correlation of the material with serum C4 level. Rheumatoid synovial fluids generally contained higher levels than serum, and five of 23 contained very much higher levels. The frequency of elevated levels of immune complex-like material in sera of patients with systemic lupus erythematosus (2 of 29) and with miscellaneous vasculitides (2 of 21 was much lower than in RA, suggesting that mRF exhibits a specificity for only certain kinds of immune complexes. The reason for this apparent specificity may explain such distinctive features of RA as the high frequency of polyclonal RF, the lack of immune complex nephritis, and the generally normal levels of serum complement.

Heterogeneity of IgM/IgG cryocomplexes: immunological-clinical correlation

A detailed study has been made of the mixed cryoglobulins (MCs) occurring in four patients with different disease states. These included (1) macroglobulinemia of Waldenström with an IgM(K)/IgG cryocomplex containing Clq, free DNA, rheumatoid factor, anti-ssDNA and VDRL activity; (2) Peetom-Meltzer syndrome with an IgM(K)/IgG cryocomplex containing free DNA, Clq, Cls, fibrinogen, alpha2-macroglobulin and beta-lipoprotein; (3) rheumatoid arthritis with an IgM(K)/IgG cryocomplex containing rheumatoid factor, free DNA and anti-ssDNA activity; and (4) angioimmunoblastic lymphadenopathy with an IgM(K)/IgG cryocomplex containing rheumatoid factor, free DNA and anti-I cold agglutinin activity. All of these patients exhibited multisystem involvement with evidence of vascular injury. A review of the MCs found in various clinical states, reveals that whereas in systemic lupus erythematosus MCs almost invariably possess antinuclear factor activity and contain DNA as well as some components of complement, in Peetom-Meltzer syndrome MCs do not have these characteristics, but invariably have strong rheumatoid factor activity, usually absent in MCs from systemic lupus erythematosus. MCs in lymphoproliferative disorders have strong rheumatoid factor activity but not ANF activity. In infectious diseases, MCs usually exhibit strong rheumatoid factor, VDRL and cold agglutinin activity, and co-precipitate with alpha2-macroglobulin. While there is some overlap in the characteristics of MCs from various clinical diseases, the above mentioned differences are probably of some biological importance and require further investigation.

Catabolism of human IgG in mice sensitized to various IgG fragments. Similarities to the catabolism of rheumatoid IgG in mice

Whole body elimination studies of human serum IgG have showm that C57Bl miceare tolerant to this protein at low concentrations. The present study demonstrates that tolerance to this protein may be broken by presensitization of the mouse with the pepsin-derived fragments of human IgG (F(ab)2 and pFc), in marked contrast to the papain-derived fragments (Fab and Fc). Sensitization with F(ab)2 fragments induced a distinctive elimination pattern of the intact protein which was analogousto that observed in non-sensitized mice injected with serum IgG isolated from patients with rheumatoid arthritis. Since, by circular dichroism studies, we have previouslyimplicated a structural anomaly at or near the hinge region of the 'rheumatoid' IgGmolecule, our observations are discussed in relationship to a possible immune aetiologyfor rheumatoid arthritis.

Free rheumatoid factor in dental periapical lesions and gingivae of patients with rheumatoid disease

To determine whether evidence of rheumatoid inflammation, in the form of free rheumatoid factor, might be found in the teeth-supporting tissues of patients with known rheumatoid disease, tissues from the dental periapical lesions of one group of 50 rheumatoid and 23 control patients, and from the marginal gingivae of a second group of 58 rheumatoid patients were examined by the direct immunofluorescence technique that employed fluroesceinisothiocyanate (FITC)-labelled aggregated human IgG. The gingival tissues contained no free rheumatoid factor. Free rheumatoid factor-producing plasma cells were, however, detected in the dental periapical lesions of 3 of the 50 rheumatoid patients, i.e. in 6%, and in 1 of the control patients i.e., in 4%. This control patient had suffered from nephritis 10 months prior to the investigation. Because free rheumatoid factor did occur, albeit infrequently, in the dental periapical lesions of rheumatoid patients, a search for IgG rheumatoid factor, known to occur in greater abundance than the IgM type although "hidden", was indicated.

Studies into the occurrence of soluble antigen-antibody complexes in disease. VI. Further characterization of the biological and physical properties of the rheumatoid biologically active factor (RBAF)

The rheumatoid biologically active factor (RBAF) was characterized further with respect to its biological and physical characteristics. The histamine-releasing activity of the RBAF in the guinea-pig lung was influenced in the same manner as soluble immune complexes when the lungs were being perfused at 20°C or 45°C or when the perfusate lacked calcium or magnesium or contained N-ethylmaleimide, phenol, theophylline, adrenaline or succinate. The RBAF was consistently associated with complement-fixing activity and RBAF-positive synovial fluid showed a lower total haemolytic complement level than RBAF-negative fluid. However, RBAF activity was not lost following absorption with anti-human beta 1C globulin. There was a higher frequency of free DNA and/or single-stranded DNA in RBAF-positive than negative synovial fluid. RBAF-positive synovial fluid was more active than RBAF-negative fluid in neutrophil chemotaxis when examined at 1:10 but not when undiluted. Mixed IgG–IgM cryoprecipitates failed to show RBAF activity and aggregates seen on analytical ultracentrifugation of rheumatoid synovial fluid did not correspond with the RBAF. The RBAF was stable to freezing and thawing but was labile to acid pH and to heating at 56°C. It was concluded that the RBAF is likely to be a soluble immune complex consisting of IgG and a second constituent which is labile to acid and heat.