Immunoglobulin E-rheumatoid factor in the serum of patients with rheumatoid arthritis, asthma, and other diseases

Glycan and Peptide IgE Epitopes of the TNF-alpha Blockers Infliximab and Adalimumab - Precision Diagnostics by Cross-Reactivity Immune Profiling of Patient Sera

Biological drugs like therapeutic antibodies are widely used for the treatment of various diseases like inflammatory disorders and cancer. A drawback of these novel treatments is the substantial proportion of patients experiencing adverse reactions such as loss-of-drug effect or hypersensitivity reactions. These reactions are associated with pre-existing and/or developing anti-drug antibodies. Especially IgE development is a risk factor for life-threatening systemic anaphylaxis.

Methods: In order to characterize the individual drug-specific serum IgE, an IgE cross-reactivity immune profiling (ICRIP) assay was developed. Individual IgG epitopes of anti-drug antibodies against adalimumab were identified by epitope mapping via peptide microarray.

Results: ICRIP analyses of sera from patients treated with the therapeutic antibodies adalimumab (ADL) and infliximab (IFX) reveal individual, distinct IgE binding patterns. IgG epitopes were identified mostly located in the variable region of ADL.

Conclusions: Using ICRIP and peptide microarrays for pharmacovigilance of the TNF-α blockers IFX and ADL, risk factors and biomarkers before and during therapy shall be identified. These diagnostic systems provide the basis for a safe and efficacious therapy decision for each patient in cases of adverse drug reactions mediated by different types of anti-drug antibodies.

Contribution of autoallergy to the pathogenesis in the NOD mice

The immunoglobulin isotype IgE is commonly associated with allergy. However, its involvement in autoimmune disease in general, and Type 1 diabetes (T1D) in particular, is still not completely clarified, nonetheless IgE has been observed in patients with T1D. In this article, we aimed to elucidate the contribution of IgE in the pathogenesis of the disease in a spontaneous model for T1D, i.e. the NOD mouse. We observed increased levels of IgE in splenic, lymph node and peripheral blood B cells in the NOD mice compared to the control C57BL/6 (B6) mice. No correlation was found between the IgE levels on B cells and those in the sera of these mice, indicating a B cell intrinsic property mediating IgE capture in NOD. Functionally, the B cells from NOD were similar to B6 in rescuing the IgE-mediated immune response via the low affinity receptor CD23 in a transgenic adoptive transfer system. However, the involvement of IgE in diabetes development was clearly demonstrated, as treatment with anti-IgE antibodies delayed the incidence of the diabetes in the NOD mice compared to the PBS treated group. Pancreas sections from a 13-week-old NOD revealed the presence of tertiary lymphoid structures with T cells, B cells, germinal centers and IgE suggesting the presence of autoantigen specific IgE. Our study provides an insight to the commonly overlooked immunoglobulin IgE and its potential role in autoimmunity.

Linking allergy to autoimmune disease

Type I allergy is a classical Th2-driven hypersensitivity disease based on IgE recognition of environmental allergens. Exposure of allergic individuals to exogenous allergens leads to immediate type inflammation caused by degranulation of mast cells via IgE-allergen immune complexes and the release of inflammatory mediators, proteases and pro-inflammatory cytokines. However, allergic inflammation can occur and persist in the absence of exposure to exogenous allergens and might paradoxically resemble a Th1-mediated chronic inflammatory reaction. We summarize evidence supporting the view that autoimmune mechanisms might contribute to these processes. IgE recognition of autoantigens might augment allergic inflammation in the absence of exogenous allergen exposure. Moreover, autoantigens that activate Th1-immune responses could contribute to chronic inflammation in allergy, thus linking allergy to autoimmunity.

The mouse mast cell-restricted tetramer-forming tryptases mouse mast cell protease 6 and mouse mast cell protease 7 are critical mediators in inflammatory arthritis

OBJECTIVE

Increased numbers of mast cells (MCs) that express beta tryptases bound to heparin have been detected in the synovium of patients with rheumatoid arthritis (RA). The corresponding tryptases in mice are mouse MC protease 6 (mMCP-6) and mMCP-7. Although MCs have been implicated in RA and some animal models of arthritis, no direct evidence for a MC-restricted tryptase in the pathogenesis of inflammatory arthritis has been shown. We created transgenic mice that lack heparin and different combinations of mMCP-6 and mMCP-7, to evaluate the roles of MC-restricted tryptase-heparin complexes in an experimental model of arthritis.

METHODS

The methylated bovine serum albumin/interleukin-1beta (mBSA/IL-1beta) experimental protocol was used to induce inflammatory monarthritis in different mouse strains. Mice were killed at the time of peak disease on day 7, and histochemical methods were used to assess joint pathology.

RESULTS

Arthritis was induced in the knee joints of mBSA/IL-1beta-treated mMCP-6(+)/mMCP-7(-) and mMCP-6(-)/mMCP-7(+) C57BL/6 mice, and numerous activated MCs that had exocytosed the contents of their secretory granules were observed in the diseased mice. In contrast, arthritis was markedly reduced in heparin-deficient mice and in mMCP-6(-)/mMCP-7(-) C57BL/6 mice.

CONCLUSION

MC-derived tryptase-heparin complexes play important roles in mBSA/IL-1beta-induced arthritis. Because mMCP-6 and mMCP-7 can compensate for each other in this disease model, the elimination of both tryptases is necessary to reveal the prominent roles of these serine proteases in joint inflammation and destruction. Our data suggest that the inhibition of MC-restricted tryptases could have therapeutic potential in the treatment of RA.

Synovial mast cells: role in acute and chronic arthritis

Mast cells reside in the normal synovium and increase strikingly in number in rheumatoid arthritis and other joint diseases. Given the broad spectrum of activity of this lineage, it has for decades been considered probable that mast cells are involved in the pathophysiology of synovitis. Recent work in murine arthritis has substantiated this suspicion, showing that mast cells can contribute importantly to the initiation of inflammatory arthritis. However, the role of the greatly expanded population of synovial mast cells in established arthritis remains unknown. Here we review the current understanding of mast cell function in acute arthritis and consider the potentially important influence of this cell on key processes within the chronically inflamed synovium, including leukocyte recruitment and activation, fibroblast proliferation, angiogenesis, matrix remodeling, and injury to collagen and bone. We also consider recent evidence supporting an immunomodulatory or anti-inflammatory role for mast cells as well as pharmacologic approaches to the mast cell as a therapeutic target in inflammatory arthritis.

Mast cells as a target in the treatment of rheumatoid arthritis

Mast cells represent a unique cell population, which is involved in a number of immune responses in our body. Mast cells (MCs) release an array of potent pro-inflammatory mediators and cytokines upon activation that are either pre-stored in the granules or synthesised de novo. These mediators can make a substantial contribution to the initiation and perpetuation of the inflammatory processes. This review provides an insight for the potential role of MCs in rheumatoid arthritis (RA). The data on mast cell distribution in the rheumatoid joint along with the information obtained from in vitro experiments and observations in animal models suggest that these cells may be involved in RA. The encouraging results of MC inactivating therapy in animal models of arthritis indicate that MC stabilizers may prove beneficial as a supplementary therapy in RA.

The anti-IgE/anti-FcepsilonRIalpha autoantibody network in allergic and autoimmune diseases

Basophil granulocytes and tissue mast cells and their mediators play a role in the pathogenesis of several immune and inflammatory disorders. Human basophils and mast cells (FcepsilonRI+ cells) can be activated through immunological interaction with the IgE-FcepsilonRI network. FcepsilonRI+ cells can be triggered by cross-linking between the Fab portions of IgE and multivalent antigens (direct anaphylaxis). 'Reverse type' anaphylaxis can occur through three distinct mechanisms: antibodies against the Fcepsilon portion of IgE (anti-IgE), antibodies against epitopes of the alpha chain of FcepsilonRI (anti-FcepsilonRIalpha) and anti-IgG acting on IgG-IgE complexes bound to FcepsilonRI. Anti-IgE autoantibodies are occasionally present even in normal donors and more frequently in a variety of allergic (chronic urticaria, atopic dermatitis and bronchial asthma) and autoimmune disorders (rheumatoid arthritis, lupus erythematosus and systemic sclerosis). IgG anti-IgE from a small percentage of patients induces the release of mediators from human FcepsilonRI+ cells. Some of the anti-IgE autoantibodies present in allergic patients are non-anaphylactogenic, thus representing a possible protective mechanism preventing the association of IgE with FcepsilonRI. Anti-FcepsilonRIalpha autoantibodies also occur in a significant percentage of patients of chronic urticaria and probably non-allergic asthma and some autoimmune diseases. Although anti-IgE and anti-FcepsilonRIalpha autoantibodies, present in a percentage of patients with immune disorders, are relevant to the pathogenesis of these conditions, much remains to be learnt about their immunochemistry, their prevalence and precise role in various inflammatory diseases.

Human synovial mast cells. I. Ultrastructural in situ and in vitro immunologic characterization

OBJECTIVE

To examine the ultrastructure of human synovial mast cells in situ, to identify immunologic and nonimmunologic stimuli that activate these cells in vitro, and to quantify a number of preformed and de novo-synthesized mediators.

METHODS

We conducted an ultrastructural study of synovial mast cells in situ and performed immunoelectron microscopy localization of tryptase and chymase. Isolated synovial mast cells were analyzed biochemically, immunologically, and functionally in vitro and compared with cells from human lung, heart, and skin.

RESULTS

Ultrastructural study of synovial tissue revealed mast cells with homogeneously dense, scrolled, crystal, and mixed granules, and lipid bodies in the cytoplasm. A small percentage of mast cells showed evidence of degranulation. Immunoelectron microscopy demonstrated the subcellular localization of tryptase and chymase over granules of > 90% of the mast cells, which were of the MCTC subtype. Isolated synovial mast cells released histamine in response to immunologic (anti-IgE and anti-Fc epsilon receptor I [anti-Fc epsilon RI]) and nonimmunologic (substance P, recombinant human stem cell factor, and 48/80) stimuli, but did not respond to recombinant human C5a in vitro. Synovial mast cells differed from those isolated from other human tissues, in a variety of immunologic and biochemical features. There was a linear correlation between the percentage of histamine secretion and tryptase release (r = 0.79, P < 0.001) induced by cross-linking of Fc epsilon RI. Cross-linking of IgE with anti-IgE on synovial mast cells induced de novo synthesis of prostaglandin D2 (mean +/- SEM 87.5 +/- 4.9 ng/10(6) cells) and of leukotriene C4 (57.6 +/- 17.8 ng/10(6) cells).

CONCLUSION

Mast cells ultrastructurally characterized in situ in synovial tissue were seen to differ from mast cells previously isolated from other human tissues. This raises the possibility that the local microenviroment influences their phenotype. Isolation of mast cells from human synovia can be useful for studying their role and their mediators in patients with arthritis.

Mast cell activation in human synovium explants by calcium ionophore A23187, compound 48/80, and rabbit IgG anti-human IgE, but not morphine sulfate

To investigate human synovial mast cell physiology, we developed a model in which mast cells in human synovial explant cultures were activated by immunologic or non-immunologic mechanisms. Small (3 mm) cubes of synovial membrane were incubated with or without secretagogue for 30, 45 or 60 min, and supernatant histamine concentrations were quantified. We measured significant histamine release with compound 48/80 at concentrations > or = 1 mg/ml, and with calcium ionophore A23187 at > or = 5 micrograms/ml. Rabbit IgG anti-human IgE induced significant histamine release at all concentrations tested, maximum at 78 micrograms/ml. Morphine sulfate produced no histamine release from synovial explants, in contrast to its significant stimulation of histamine release from neonatal foreskin explants in our explant system. We confirmed synovial mast cell degranulation by electron microscopy, and showed that it corresponded with measurable histamine release. Furthermore, histamine release was not due to secretagogue-induced cytotoxicity, as assessed by supernatant lactate dehydrogenase levels and by ultrastructural analysis. Since morphine sulfate induces mast cell degranulation and histamine release in adult and neonatal human skin, our data show that although synovial and dermal mast cells have a similar granule enzyme profile and electron microscopic morphology, they differ in functional responses. These observations support recent data that among similar human mast cell subtypes there are physiologic differences. Finally, our explant model will be useful in studies of mast cell involvement in arthritis.

The effect of intra-articular capsaicin on passive synovial anaphylaxis and blood flow in the rat knee joint

Normal rat and human synovium is innervated by small diameter, unmyelinated, peptide-containing nerves. A close anatomical association between these nerves and mast cells has been postulated23, although functional interactions have not been described. Capsaicin is frequently used to activate sensory nerves and we have examined both acute and long-term effects of capsaicin on passive synovial anaphylaxis (PSA) and blood flow in the rat knee joint. The acute injection of capsaicin into the synovial space (330 nmol, 30 min prior to antigen) significantly inhibited plasma extravasation into the joint tissues (measured by accumulation of [125I]-human serum albumin) following PSA, and produced vasoconstriction in normal joints (measured by 133Xe clearance). There was no effect on plasma extravasation when capsaicin was injected 3 h prior to antigen. Inhibition of the PSA response following acute intra-articular capsaicin was not reversed by pretreatment with the cyclo-oxygenase inhibitor indomethacin (to inhibit thromboxane generation) or in rats chronically treated with guanethidine (to deplete noradrenaline from post-ganglionic sympathetic fibres). Further, a longer term pre-treatment of the joints with a single intra-articular injection of capsaicin (3.3 mumol) also attenuated plasma extravasation following induction of PSA 7 days later, and was accompanied by a non-significant decrease in joint blood flow. Plasma extravasation in response to compound 48/80, a non-immunological mediator of mast-cell degranulation, was not affected in joints treated with capsaicin 7 days previously.(ABSTRACT TRUNCATED AT 250 WORDS)

Human synovial mast cell involvement in rheumatoid arthritis and osteoarthritis. Relationship to disease type, clinical activity, and antirheumatic therapy

Mast cells were isolated by enzymatic digestion of synovium obtained from 48 patients with rheumatoid arthritis (RA) and 42 patients with osteoarthritis (OA). A significantly lower percentage of stainable synovial mast cells was obtained by tissue digestion from patients with clinically active RA compared with those with less active disease. The 54 patients treated with nonsteroidal antiinflammatory drugs had a significantly lower percentage of stainable synovial mast cells in cell suspension than did the other 36 patients. When anti-IgE antibody was used as a secretagogue in vitro, significantly greater histamine release was observed from synovial mast cells of RA patients compared with OA patients. Greater histamine release in response to anti-IgE was observed in the RA patients with more clinically active disease and those who were treated with prednisone, compared with RA patients without these features. Synovial mast cells of RA patients treated with a disease-modifying antirheumatic drug had a significantly lower mean histamine content than did cells from patients not receiving such treatment. Our data suggest that there are differences between synovial mast cells from tissues of patients with RA and OA and suggest that synovial mast cells may be activated in clinically active RA. In addition, the data indicate an effect of systemic antirheumatic therapy on mast cells isolated from synovium of patients with arthritis.

Rheumatoid arthritis, food, and allergy

One of the most promising lines of research on the etiology and pathogenesis of rheumatoid arthritis (RA) is its association with the genetically determined MHC class II antigens. The function of these macromolecules, presentation of antigens to the T-helper cells, supports the possibility that external antigens influence RA. We review available literature concerning the relationship between RA and food. Circumstantial evidence suggests that some foods or food components might influence subgroups of RA patients, although many of the publications on this subset do not meet acceptable standards of modern medical research.

Rheumatoid factor (RF) distribution in periodontal disease

This study investigated the occurrence of an autoantibody, IgM rheumatoid factor, that may result from the chronic inflammation noted in periodontal disease and rheumatoid arthritis. In order to detect IgM-RF, a biotin-avidin ELISA was developed. This assay was found to be sensitive and accurate by testing a rheumatoid arthritis population. The characteristics of this rheumatoid arthritis group were further determined, such that the total serum immunoglobulin concentrations were slightly elevated although within the normal range for IgM, IgG, and IgA; IgG antibody levels were elevated against oral microorganisms of the genus Capnocytophaga, while elevated IgM antibody levels were noted to Bacteroides species. In a population of 260 subjects of which 171 were periodontal disease patients, 16 of 171 (9.4%) were seropositive for IgM-RF, of which the predominant disease types were advanced destructive periodontitis and adult periodontitis. For comparison, a random population of seronegative periodontal disease patients was constructed that was matched for sex and approximate age to the seropositive group. The total immunoglobulin levels of the two groups were not significantly different and the means of both were slightly lower than the rheumatoid arthritis group. When the antibody profiles of the two periodontal disease populations were compared it became evident that the RF-positive group showed IgM and IgG antibody that was significantly elevated to Capnocytophaga species and F. nucleatum. Therefore, the chronic inflammation associated with periodontitis appears to increase significantly the formation of IgM-RF; however, there does appear to be a relationship between IgM-RF and elevated antibody to selected oral microorganisms.

In vivo effects of nonsteroidal antiinflammatory drugs on rat skin and synovial mast cell-induced vasopermeability

Using our animal model of synovial mast cell-mediated arthritis in rats, we tested the effects of 3 nonsteroidal antiinflammatory drugs (NSAIDs) (aspirin, indomethacin, and ketoprofen) and an H1 and an H2 histamine receptor antagonist (diphenhydramine and cimetidine, respectively) on synovial and dermal mast cell-induced vasopermeability. Drug effects were assessed by quantifying the leakage of radiolabeled albumin into tissues following specific antigen-initiated activation of passively sensitized dermal and synovial mast cells. The 3 NSAIDs tested had different effects on synovial and dermal mast cell-induced vasopermeability. Aspirin and indomethacin significantly increased dermal and synovial plasma exudation (P less than or equal to 0.008). Ketoprofen decreased dermal (P = 0.015), but had no effect on synovial, vascular exudation. Complete histamine H1 and H2 receptor blockade with diphenhydramine and cimetidine, respectively, substantially decreased (P less than or equal to 0.0008), but did not completely inhibit, dermal and synovial mast cell-induced vasopermeability. However, the addition of indomethacin to the combined antihistamine regimen resulted in an increase in the leakage of the radiolabel into skin and synovium (back to control levels), despite the complete blockade of H1 and H2 receptors. Results of experiments with antihistamines and indomethacin suggest that mediators other than histamine are involved in synovial mast cell-induced inflammation. Furthermore, the differential response to ketoprofen indicates that the specific antigen-stimulated mediator release profiles of dermal and synovial mast cells are different. Our finding of enhanced synovial vascular leakage in animals treated with some NSAIDs, and no such effect by other NSAIDs, perhaps explains in part the diverse effects of these agents in humans with arthritis.

Incidence and characterization of canine rheumatoid factor

Rheumatoid factor (RF) was found in titers greater than 1:8 in 72.2% of cases of classical or definite canine rheumatoid arthritis (RA) and in 5.9% or normal sera. Serum fractionation and immunoabsorbant studies that much of the RF present was IgG, although activity was demonstrated in all 3 major immunoglobulin classes. Evidence of involvement of both IgG and IgM to form complexes of varying sizes was obtained.

Newer laboratory parameters for the diagnosis of rheumatic disease

Measurement of serum autoantibodies is a useful adjunct in the diagnosis of connective tissue diseases. Approximately 15 percent of patients with rheumatoid arthritis are seronegative for rheumatoid factor by standard assays. The development of enzyme-linked immunosorbent assays for additional isotypic and idiotypic determinants may expand the diagnostic sensitivity of rheumatoid factor measurements. Although extremely sensitive, the finding of antinuclear antibodies is not highly specific for systemic lupus erythematosus and related disorders; the ability to rapidly screen serum against newly characterized specific nuclear antigens has been helpful in the diagnosis of newly described systemic lupus erythematosus subtypes, overlap syndromes, Sjögren's syndrome, and scleroderma variants. Women with unexplained recurrent fetal loss and patients with unexplained thrombotic episodes should be screened for the presence of the anticardiolipin antibody. Glycoproteins (C-reactive protein, alpha-1-glycoprotein, fibronectin) may prove useful as indicators of rheumatic disease activity and the efficacy of therapeutic intervention.

IgE rheumatoid factors: quantification in synovial fluid and ability to induce synovial mast cell histamine release

IgE rheumatoid factor activity was found to be significantly elevated (P less than 0.01) using an ELISA assay when paired synovial fluid and sera from 13 patients with active RA were compared to ten control samples. Synovial fluid IgE RF activity was higher than predicted by diffusion alone in 7/11 (64%) of the RA synovial fluids studied when coefficients of diffusion were determined. The specificity of IgE RF activity as measured by the ELISA was confirmed using immunoaffinity chromatography. Mast cells, obtained by enzymatic dispersion of rheumatoid synovial tissue, were sensitized with sera containing either IgE antibodies directed against ragweed or IgE with RF activity. Histamine was released upon challenge with anti-IgE antibodies (33.2% +/- 11), ragweed antigen E (34.6% +/- 11), or aggregated gamma globulin (47.6% +/- 17.9). No histamine release was observed if antigen challenge occurred in the absence of appropriate sensitization, with C3 anaphylatoxin, or after immunoadsorption of IgE from sera containing IgE RF activity.

Determination of IgE complexes and of total IgE by latex immunoassay

A sensitive immunoassay based on latex particle agglutination for the measurement of circulating IgE-containing complexes is described. In this method, the anti-IgE-coated particles are incubated with diluted serum and the resulting agglutination is quantified by turbidimetry or particle counting. In the latter version, the assay is fully automated in a continuous flow system. IgE-containing complexes were detected in all tested sera. Increased concentrations were observed in about 80% of the subjects with elevated serum IgE. However, high levels of IgE-complexes may also be found in subjects with a normal or even a very low serum concentration of IgE. The same latex immunoassay can be used for the determination of total IgE, after pepsin digestion of the gamma-globulin fraction of the serum. The results obtained correlate well with those found with a sandwich radioimmunoassay (r = 0.91, n = 83). The present method, however, yields a greater number of significantly positive results than the radioimmunoassay, probably because of its ability to detect IgE entrapped in circulating complexes.

IgM rheumatoid factor (RF), IgA RF, IgE RF, and IgG RF detected by ELISA in rheumatoid arthritis

One hundred patients with rheumatoid arthritis (RA), of whom 73 were seropositive by latex or Waaler-Rose (WR) assays, or both, 100 healthy subjects, and 102 diseased controls (22 patients with systemic lupus erythematosus (SLE) and 80 with bronchial asthma) were evaluated for the presence of IgM rheumatoid factor (RF), IgA RF, IgE RF, and IgG RF by an enzyme linked immunosorbent assay (ELISA). Ninety two per cent, 65%, 68%, and 66% of the patients with RA were found to be positive for IgM, IgA, IgE, and IgG respectively. A positive correlation existed between the levels of IgM RF and IgA RF on the one hand and disease activity on the other, and the levels of IgM RF and IgA RF correlated with the levels of circulating immune complexes as measured by a C1q binding assay. The presence of extra-articular features also correlated positively with the levels of IgA RF and IgE RF. Five out of six patients with Sjögren's syndrome had very high levels of IgA RF. Of 47 patients typed for HLA-DR, DR1 and DR2 were significantly more frequent in those with the highest levels of IgM RF. Conversely, DR3 was associated with low levels or absence of IgA RF and IgE RF. These results suggest that immune response genes may regulate the level of different RF isotypes. The frequencies of IgM, IgA, IgE, and IgG RF were 59%, 36%, 9%, and 27% respectively in SLE and 25%, 2.5%, 70%, and 59% in bronchial asthma.

Characterization and functional studies of rheumatoid synovial mast cells. Activation by secretagogues, anti-IgE, and a histamine-releasing lymphokine

Microscopic analysis of synovial specimens from 35 patients with rheumatoid arthritis (RA) and 7 patients with osteoarthritis revealed mast cell hyperplasia in perivascular regions, in fibrous interstitial areas, and clustered around the periphery of lymphoid aggregates. Metachromatic staining, immunofluorescence studies, and ultrastructural analysis revealed a single population of connective tissue-type mast cells with surface IgE receptors. Total extractable histamine of synovial tissue was 4.15 +/- 2.30 micrograms/gm (n = 8) for RA synovium and 0.53 +/- 0.23 microgram/gm (n = 7) for OA synovium. Mast cell secretion was assessed and specific release of histamine from RA synovial mast cells was observed following stimulation with anti-IgE (32.3%), compound 48/80 (40.1%), calcium ionophore A23187 (25.2%), and a partially purified lymphokine with histamine-releasing activity (23.9%).

IgA rheumatoid factor synthesis by dissociated synovial cells. Characterization and relationship to IgM rheumatoid factor synthesis

We examined patterns of IgA rheumatoid factor (RF) and IgM-RF synthesis by dissociated synovial cells obtained from 27 patients with seropositive rheumatoid arthritis. Synthesis of IgA-RF was observed in 19 of 34 synovial cell preparations from these patients and constituted a mean of 16% of the total IgA produced. IgA-RF expression correlated only weakly with IgM-RF production (r = 0.385) and could be dissociated from production of IgA-RF (and IgM-RF) exhibited by simultaneously obtained peripheral blood plasma cells. While wide variations were observed in the ratio of IgA-RF:IgM-RF produced by synovial B cells in the patient sample studied, remarkable consistency in the relationship of IgA-RF to IgM-RF synthesis was observed over time in different joints of the same patient. IgA-RF synthesized by dissociated synovial cells was predominantly of the IgA1 subclass and existed in both monomeric and polymeric forms. Our results are compatible with the view that local production of IgA-RF and IgM-RF are regulated independently of each other.

Articular mastocytosis in rheumatoid arthritis

The number and distribution of mast cells were assessed in 116 synovial membranes from patients with rheumatoid arthritis and in 30 control specimens. Rheumatoid synovial membranes contained a mean of 48.5 mast cells per 20 high-power fields (HPF) (range 0-252), and control synovial membranes had a mean of 3.9 mast cells per 20 HPF (range 0-13) (P less than 0.001). In a comparison of high and low mast cell subgroups in rheumatoid arthritis, counts were directly related to the intensity of clinical synovitis in the affected joint, but not to hemoglobin concentration or erythrocyte sedimentation rate. Joints excised from 5 patients with rheumatoid arthritis were characterized by active bone remodeling with increased osteoid, active resorption by osteoclasts, and trabecular osteoporosis. Mast cells were prominent in both extraosseous pannus and intraosseous invasive tissue. The possible roles of mast cells in the pathogenesis of rheumatoid arthritis are discussed.

Quantitation of human synovial mast cells in rheumatoid arthritis and other rheumatic diseases

We examined sections of synovial membranes from 14 patients with rheumatoid arthritis (RA), 7 with other rheumatic diseases, and 10 with no apparent joint disease. Patients with RA and other rheumatic diseases had significantly more synovial mast cells/vessel than patients with no joint disease (0.49 and 0.20, respectively, versus 0.03). They also had significantly more total mast cells/10 fields than patients with no joint disease (9.9 and 5.0, respectively, versus 0.4). Within the rheumatoid group, patients with active disease had more total mast cells/10 fields than patients clinically considered to have end-stage disease (P less than 0.05). Synovial basophils were not identified in any patient. Synovial vascularity was similar for all groups (2.3 vessels/field). The role of the synovial mast cell in RA and other rheumatic diseases remains to be determined.

Determination of IgE-containing immune complexes in human sera. Evaluation of polyethylene glycol precipitation of monomeric and complex IgE and of the detectability of IgE in the complexes

We studied the polyethylene (PEG) precipitability of monomeric human IgE, and of human IgE artificially complexed with rabbit anti-human IgE. At conditions where precipitation of monomeric IgE did not occur, from 0.2 to 20% of the complexed IgE was precipitated. The PEG precipitability of the complexes was inversely related to the IgE/anti-IgE ratio used for preparation of the complexes. From 1.5 to 19.2% of the IgE in the redissolved precipitates could be detected by use of a two-site IgE immunoradiometric assay, the percentage being highest for complexes formed at equivalence. We conclude that exact quantitation of circulating IgE immune complexes (IC) probably is impossible by any PEG precipitation assay. However, the optimized assay was found to be useful for identification of IgE IC in sera with total IgE concentrations below 5,000 U/ml. IgE IC were found in 5/20 sera from patients with Felty's syndrome, in 5/39 sera from patients with extrinsic allergy and high levels of specific IgE, and in 1/17 sera from immunized wasp allergics. No IgE IC were found in 20 normal human sera.

IgE class immune complexes in Felty's syndrome: characterisation of antibody activities in isolated complexes

By means of a double polyethylene glycol (PEG) precipitation and PRIST technique IgE was detected in 3% PEG precipitates and in the immune complex enriched fractions purified by solid-phase Clq adsorption from sera of 11 of 20 patients with Felty's syndrome. No correlation was found between the occurrence of complexed IgE and total protein content of the immune complex enriched material. IgE rheumatoid factor and anti-IgE antibody activity were detected in some of the immune complex fractions. Serum levels of complement C3, C4, and factor B were low in IgE immune complex positive cases. Only 4 of 20 patients with articular rheumatoid arthritis had IgE-containing immune complexes.

Association of rheumatoid factor with complement activation in rheumatoid arthritis and other diseases

Rheumatoid factor (RF) is a complement activating autoantibody. In rheumatoid arthritis (RA) the rate of catabolism of complement is closely related to the titre of RF. Therefore, we have examined whether these relationships are unique to RA or will be found in non-RA disorders in which RF may be found in the circulation. We studied patients with subacute bacterial endocarditis, leprosy, tuberculosis, and a variety of other rheumatic and vasculitic disorders. We found that in all the disorders examined the RF had a complement activating potential which was equivalent to that of the RF of RA patients. Furthermore in vivo activation of complement, as exhibited by the appearance of C3 degradation products, was significantly related to higher titres of haemolytically active RF in non-RA as well as the RA group. In these respects, therefore, the RF in RA and non-RA patients is indistinguishable. A possible survival value for RF is discussed.

Basophil histamine release induced by leukocyte nuclei in patients with rheumatoid arthritis

Leukocyte suspensions containing basophils were obtained from 23 patients with rheumatoid arthritis (RA). When these cells were incubated with leukocyte nuclei from normal persons, histamine release was seen in 11 of the 15 patients with active disease, but not in the quiescent group or in normal individuals. The dose-response curve for histamine release was similar to that obtained by specific antigen in type I allergy. By removal from and refixation to the cells of surface Ig, the release of histamine was respectively, abolished and restored, just as in similar experiments in hay fever patients. The dependence of pH for removal was also identical with that found in type I allergy. Antinuclear antibodies of the IgE class (IgE ANA) mainly directed against the granulocyte nuclei were often found in serum and on the cell surface of the RA patients, but not in normal individuals. A correlation was found between these titres in serum and on the cell surface. No correlation was found between ANA in serum and on the cell surface, on the one hand and disease activity and histamine release on the other. In a group of 12 patients with another joint disease, osteoarthrosis, only two patients showed histamine release, and in contrast to the other patients they showed swelling of more than two joints. The present investigation supports our hypothesis of an involvement of an autoimmune type I reaction directed against nuclear components in the RA disease.

Monocyte-dependent serum suppression of lymphocyte blastogenesis in Hodgkin's disease: an association with nephrotic syndrome

A factor inhibitory to PHA-induced lymphocyte blastogenesis was found to be present in the serum of a patient with advanced Hodgkin's disease and nephrotic syndrome. The inhibitory activity for both syngeneic and allogeneic lymphocytes was dependent on the presence of peripheral blood monocytes. The Raji-cell serum assay, as well as immunofluorescence and light and electron microscopy of the renal biopsy, showed no evidence of immune complexes. Nevertheless, a high serum IgE level as well as the finding that ultracentrifugation and heating at 56 degrees C significantly reduced the inhibitory activity (P less than 0.01) suggested the possibility that an immune complex might have mediated the suppressive activity. Treatment of the Hodgkin's disease with combined chemotherapy caused a marked reduction in the monocyte-dependent serum inhibitory activity which in turn coincided with a prompt remission of the nephrotic syndrome and marked regression of disease.