Serum levels of IgG, IgM, and IgA in rheumatoid arthritis

Exhaled Nitric Oxide Reflects the Immune Reactions of the Airways in Early Rheumatoid Arthritis

Patients with rheumatoid arthritis (RA) have altered levels of exhaled nitric oxide (NO) compared with healthy controls. Here, we investigated whether the clinical features of and immunological factors in RA pathogenesis could be linked to the NO lung dynamics in early disease. A total of 44 patients with early RA and anti-citrullinated peptide antibodies (ACPAs), specified as cyclic citrullinated peptide 2 (CCP2), were included. Their exhaled NO levels were measured, and the alveolar concentration, the airway compartment diffusing capacity and the airway wall concentration of NO were estimated using the Högman-Meriläinen algorithm. The disease activity was measured using the Disease Activity Score for 28 joints. Serum samples were analysed for anti-CCP2, rheumatoid factor, free secretory component, secretory component containing ACPAs, antibodies against Porphyromonas gingivalis (Rgp) and total levels of IgA, IgA1 and IgA2. Significant negative correlations were found between the airway wall concentration of NO and the number of swollen joints (Rho -0.48, p = 0.004), between the airway wall concentration of NO and IgA rheumatoid factor (Rho -0.41, p = 0.017), between the alveolar concentration and free secretory component (Rho -0.35, p = 0.023) and between the alveolar concentration and C-reactive protein (Rho -0.36, p = 0.016), but none were found for anti-CCP2, IgM rheumatoid factor or the anti-Rgp levels. In conclusion, altered NO levels, particularly its production in the airway walls, may have a role in the pathogenesis of ACPA-positive RA.

Evidence of variable human Fcγ receptor-Fc affinities across differentially-complexed IgG

Antibody-mediated effector functions are widely considered to unfold according to an associative model of IgG-Fcγ receptor (FcγR) interactions. The associative model presupposes that Fc receptors cannot discriminate antigen-bound IgG from free IgG in solution and have equivalent affinities for each. Therefore, the clustering of Fcγ receptors (FcγR) in the cell membrane, cross-activation of intracellular signaling domains, and the formation of the immune synapse are all the result of avid interactions between the Fc region of IgG and FcγRs that collectively overcome the individually weak, transient interactions between binding partners. Antibody allostery, specifically conformational allostery, is a competing model in which antigen-bound antibody molecules undergo a physical rearrangement that causes them to stand out from the background of free IgG by virtue of greater FcγR affinity. Various evidence exists in support of this model of antibody allostery, but it remains controversial. We report observations from multiplexed, label-free kinetic experiments in which the affinity values of FcγR were characterized for covalently immobilized, captured, and antigen-bound IgG. Across the strategies tested, receptors had greater affinity for the antigen-bound mode of IgG presentation. This phenomenon was observed across multiple FcγRs and generalized to multiple antigens, antibody specificities, and subclasses. Furthermore, the thermodynamic signatures of FcγR binding to free or immune-complexed IgG in solution differed when measured by an orthogonal label-free method, but the failure to recapitulate the trend in overall affinity leaves open questions as to what additional factors may be at play.

Immunoglobulin deficiencies in treated patients suffering from rheumatoid arthritis

Immunoglobulins and antibodies to immunoglobulins (autoimmunoglobulins) have been identified to be implicated in the pathogenesis of rheumatoid arthritis (RA). Immunoglobulin deficiencies have been suggested to account for the increased risk of infections in RA patients. This study was carried out to determine the prevalence of immunoglobulin deficiencies in patients with RA and the identification of putative contributing factors. Immunoglobulin levels in blood samples of patients with rheumatoid arthritis were evaluated by an immunonephelometric assay. Demographic and disease related data (including age, sex, smoking habits, disease duration and activity, inflammatory markers) were assessed, and associations were identified by regression analysis. 539 patients were enrolled between 2011 and 2013. The most common immunoglobulin (Ig) deficiencies were those of IgM (24.5%) and IgG (19.9%). Most frequent deficiencies of subclasses were observed for IgG1 (42.3%), followed by IgG4 (10.4%), IgG2 (7.2%), and IgG3 (5.4%). Regression analyses revealed that deficiencies of IgM, IgG, IgG1, and IgG2 were more prevalent in older patients. In addition, smoking was associated with IgG2 deficiency, and IgA deficiency was associated with female sex. Occurrence of infections was significantly increased in patients with IgG, IgG2, and IgG4 deficiencies. RA patients displayed high rates of IgG and IgM deficiencies. In consequence, the assessment of immunoglobulin status should precede the application of immune modulating drugs to prevent a potential risk of infectious diseases. Prospective studies are needed to investigate the influence of immune modulating drugs on IgG and IgG subclass levels.

Heightened Levels of Antimicrobial Response Factors in Patients With Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic progressive autoimmune disease leading to considerable disability over time. The disease can be characterized by the presence of multiple autoantibodies in the serum and synovial fluid. Microbial dysbiosis is proposed to play a role in the pathogenesis of RA. Increased systemic bacterial exposure leads to elevated levels of antimicrobial response factors (ARFs) in the circulation. In the present study, we tested whether RA patients have increased levels of ARFs by analyzing the levels of multiple ARFs in serum from RA patients and healthy age and sex-matched controls. The levels of soluble CD14 (sCD14), lysozyme, and CXCL16 were significantly elevated in RA patients compared to healthy controls. Lipopolysaccharide binding protein (LBP) levels remained unchanged in RA patients compared to healthy controls. A positive correlation of LBP with rheumatoid factor (RF) was also found in RA subjects. Interestingly, the levels of anti-endotoxin core antibodies (EndoCAb) IgM, total IgM, EndoCAb IgA, and total IgA were significantly elevated in RA patients compared to healthy controls. No significant changes in the levels of EndoCAb IgG and total IgG were observed in RA patients compared to healthy controls. Furthermore, lysozyme and CXCL16 levels were positively correlated with disease severity among RA subjects. Increases in the levels of several ARFs and their correlations with clinical indices suggest systemic microbial exposure in the RA cohort. Modulation of microbial exposure may play an important role in disease pathogenesis in individuals with RA.

Immunodietica: A data-driven approach to investigate interactions between diet and autoimmune disorders

Autoimmunity is on the rise around the globe. Diet has been proposed as a risk factor for autoimmunity and shown to modulate the severity of several autoimmune disorders. Yet, the interaction between diet and autoimmunity in humans remains largely unstudied. Here, we systematically interrogated commonly consumed animals and plants for peptide epitopes previously implicated in human autoimmune disease. A total of fourteen species investigated could be divided into three broad categories regarding their content in human autoimmune epitopes, which we represented using a new metric, the Gershteyn-Ferreira index (GF index). Strikingly, pig contains a disproportionately high number of unique autoimmune epitopes compared to all other species analyzed. This work uncovers a potential new link between pork consumption and autoimmunity in humans and lays the foundation for future studies on the impact of diet on the pathogenesis and progression of autoimmune disorders.

Development and Evaluation of a Physiologically Based Pharmacokinetic Model for Predicting the Effects of Anti-FcRn Therapy on the Disposition of Endogenous IgG in Humans

This work scaled up a previously developed physiologically based pharmacokinetic model to predict the effects of anti-FcRn agents on the disposition of endogenous IgG in human subjects. Simulations were performed with the scaled model to predict the effects of single- and multiple-dose administration of anti-FcRn monoclonal antibodies (1-256 mg/kg) and high-dose intravenous immune globulin (0.4-2 g/kg). The model was evaluated for prediction accuracy through comparison to the effects of rozanolixizumab, an anti-FcRn monoclonal antibodies under current clinical evaluation, on the disposition of endogenous IgG in healthy human subjects. The model provided reasonably accurate predictions of the effects of rozanolixizumab. Prediction errors for the maximum reduction in endogenous IgG concentrations were -8.50% (90% model prediction interval: -14.0% to 1.44%), 3.33% (90% model prediction interval: -13.9% to 21.2%), and 6.85% (90% model prediction interval: -35.2% to 10.5%) for rozanolixizumab doses of 1, 4, and 7 mg/kg, respectively. Model simulations predict that anti-FcRn therapies will exhibit greater dose potency in healthy volunteers than in patients with elevated IgG production rates (e.g., as typically found in autoimmune disease). The model appears to have potential for use in assessing and predicting novel dosing strategies for anti-FcRn therapies.

Elevated Membrane and Soluble CD64: A Novel Marker Reflecting Altered FcγR Function and Disease in Early Rheumatoid Arthritis That Can Be Regulated by Anti-Rheumatic Treatment

OBJECTIVES

Fc receptors (FcR) interacting with immune complexes (ICs) is a central event in the immune pathogenesis of rheumatoid arthritis (RA). Here we asked if a specific FcR is linked to RA pathogenesis and if FcR activities relate to disease and treatment outcome in early RA.

MATERIAL AND METHODS

Twenty autoantibody-positive RA patients and 33 HC were included. The patients were evaluated before and after treatment with methotrexate and prednisolone. At follow-up, the EULAR response criteria were applied to determine the individual treatment outcomes. Serum immunoglobulin levels were measured and the expression of FcR for IgG (FcγR) and IgA (FcαR) on peripheral blood monocytes were determined by flow cytometry. The monocytic FcγR function was evaluated by human IgG1 and IgG3 IC-binding and TNFα stimulated release. Plasma levels of soluble FcRs (sFcRs) were determined with ELISA.

RESULTS

The IgG1 and IgG3 levels were elevated in the RA sera. The RA monocytes expressed more CD64 and cell surface-bound IgG than HC monocytes, and showed an impaired FcγR function as reflected by changes in IC-binding and decreased IC-stimulated TNFα secretion. These findings correlated significantly with different disease activity markers. Furthermore, sFcRs were elevated in the patient plasma, and sCD64 was specific for RA (compared with a reference group of patients with active psoriatic arthritis). Following treatment, immunoglobulins and sFcR levels were reduced, whereas membrane CD64 was only decreased in patients with good response to treatment.

CONCLUSIONS

Early RA patients display increased membrane and soluble CD64 and an impaired FcγR function correlating with joint disease activity. Beneficial responses of anti-rheumatic treatment in patients reduce CD64. These data suggest sCD64 as an important objective biomarker in RA.

IgG and IgA antibody titers against human heat-shock protein (hsp60) in sera of rheumatoid arthritis and osteoarthritis patients

Abstract To learn whether heat-shock proteins (HSP) are involved in the pathogenesis of rheumatoid arthritis (RA), antirecombinant human heat-shock protein 60 (hsp60) IgG and IgA in sera of RA and osteoarthritis (OA) patients were investigated. Only the anti-hsp60 IgG titer of seropositive (RF-positive) patients was found to be elevated. Although RF titers of the sera of seropositive RA patients were increased, there was no correlation between the individual anti-hsp60 IgG titer and the corresponding RF titer. In contrast, all the anti-hsp60 IgA titers of the sera of OA, seronegative RA, and seropositive RA patients were found to be elevated. Among them, only the serum IgA concentration of seropositive RA patients was increased. Thus, it was suggested that the increased anti-hsp60 IgG reflects the pathogenesis of RA and its activity. It was also suggested that the increased anti-hsp60 IgA response reflects an involvement of hsp60 in the pathogenesis of arthritides rather than the pathogenesis of RA.

Serum immunoglobulins and the risk of rheumatoid arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is associated with several autoantibodies that can precede the clinical disease. The immunoglobulin concentrations in serum samples before illness were studied to learn more about the immunological process before RA.

METHODS

A case-control study was nested within a Finnish cohort of 19,072 adults who had neither arthritis nor a history of it at the baseline examination during 1973-1977. By late 1989, 124 had developed RA, of which 89 were positive for rheumatoid factor (RF). Three controls per each incident case were individually matched for sex, age, and municipality. The concentrations of IgG, IgA, and IgM were measured from stored serum samples.

RESULTS

Serum IgG before illness was found to be directly proportional to the risk of RF positive RA, and a non-linear association was present between serum IgA and the risk of RF positive RA. These associations were constant between men and women and other subgroups of the study population and not confounded by serum orosomucoid concentration, level of education, smoking, alcohol intake or body mass index. As adjusted for these factors, the odds ratios (95% confidence intervals) of RF positive RA in the lowest, mid, and highest tertiles of IgG distribution were 1.00, 1.55 (0.81, 2.97), and 2.22 (1.16, 4.26), and in the tertiles of IgA 1.00, 2.23 (1.14, 4.36), and 1.78 (0.89, 3.57), respectively. The associations persisted throughout the entire observation period but were most distinct when the period to the onset of clinical RA was > or = 10 years. IgM carried no predictive significance. None of the serum immunoglobulins predicted the development of RF negative RA.

CONCLUSIONS

Increased IgG levels may reflect some, at present unknown process in the early events leading to the development of RA, typically occurring > or = 10 years before the onset of clinical disease.

Evidence for differential effects of sulphasalazine on systemic and mucosal immunity in rheumatoid arthritis

OBJECTIVE

To study the effects of sulphasalazine (SASP) on the systemic and mucosal humoral immune systems in patients with rheumatoid arthritis (RA).

METHODS

Serum concentrations of interleukin 6 (IL-6), class and subclass specific IgG, IgA and IgM, IgA and IgG antigliadin antibodies and rheumatoid factors (RF) of IgG, IgA (including IgA1 and IgA2 subclasses) and IgM isotypes were measured before and 16 weeks after sulphasalazine (SASP) therapy in 15 female and three male patients with RA. Amounts of immunoglobulins in saliva and jejunal fluid were measured as estimates of mucosal humoral immunity.

RESULTS

Serum concentrations of IgA and IgG decreased significantly during SASP therapy and correlated with reduced concentrations of IL-6. In addition, levels of circulating IgA RF, IgA anti-gliadin antibodies and IgM RF decreased significantly after the treatment. In contrast, immunoglobulin levels in saliva and jejunal fluid were unaltered.

CONCLUSION

SASP exerts powerful but selective inhibitory effects on systemic immunoglobulin production, whereas no effects on mucosal immunoglobulin production were observed. The decreased systemic B cell activity may be mediated by downregulation of the production of IL-6, a cytokine with Ig switching properties.

The clinical value of measuring immunoglobulins when assessing penicillamine therapy in rheumatoid arthritis

Immunoglobulins are often high in active rheumatoid arthritis and fall when treatment with a slow-acting anti-rheumatic drug is instituted. We assessed the value of monitoring immunoglobulins during penicillamine therapy; 145 patients were followed for up to 5 years, IgA, IgM and IgG levels were compared to 12 other clinical and laboratory variables on 903 occasions. Mean levels of IgA and IgG fell by 10-30%. These changes were less than with ESR or clinical measures such as articular index and duration of morning stiffness. Immunoglobulin levels showed weak correlations with other variables. Only a small number of patients had hypogammaglobulinemia. Initially, 5 cases had low IgA with subsequent falls in 3 more. Initially, 2 cases had low IgG with subsequent falls in 5 more. No patients had low IgM levels. These changes seemed clinically irrelevant. Radiological progression was related to IgA levels. Patients with persistently high rates of radiological progression had persistently higher serum IgA. We conclude that IgM gives the most "acute phase" pattern of response. IgA gives more theoretically interesting information, especially concerning radiological progression. There is only a limited amount of clinically valuable information gained from measuring immunoglobulins.

The relation of radiographic changes to serum acute-phase proteins and rheumatoid factor in 200 patients with rheumatoid arthritis

Radiographic parameters in 200 patients with rheumatoid arthritis (RA) were correlated with laboratory parameters, including hemoglobin (Hb), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), orosomucoid (OROS), immunoglobulin G (IgG), IgM, IgA, and rheumatoid factor (RF). CRP, OROS, and Hb showed a significant association with the severity and progress of radiographic parameters. ESR and WARO showed a significant association with the severity of radiographic parameters in late RA only. IgG, IgM, and IgA did not show any significant correlation with radiographic parameters.

Correlation of immunoglobulin and C reactive protein levels in ankylosing spondylitis and rheumatoid arthritis

Serum C reactive protein (CRP), IgG, and IgA levels were measured in 22 patients with ankylosing spondylitis (AS) and in 20 patients with rheumatoid arthritis (RA) to study the regulation of these proteins in inflammatory disease states. In both RA and AS the mean CRP, IgG, and IgA levels were raised above normal values. Although IgA and CRP levels showed a significant positive correlation in RA (r = 0.53, p = 0.02), there was no correlation between these values in AS (r = 0.24, p = 0.29). The difference in correlation coefficients between the AS and RA groups was significant at a p = 0.05 level. In RA the raised IgA levels may be another manifestation of the acute phase response, as shown by the good correlation between IgA and CRP in that disease. In AS, however, the IgA levels, although raised, do not correlate with CRP levels, suggesting that the mechanism of increase of IgA in the two diseases is different. Gut mediated immune stimulation has been proposed as a cause of raised IgA levels in AS.

Effect of drug therapy on circulating and synovial fluid Ig-secreting cells in rheumatoid arthritis

A common immunological abnormality in rheumatoid arthritis (RA) is an increased spontaneous polyclonal B cell activation. In order to study the influence of drug therapy in RA on the functional activity of B cells we enumerated spontaneous plaque-forming cells (PFC) in peripheral blood lymphocytes (PBL) and synovial fluid lymphocytes (SFL) by a reverse haemolytic plaque assay. Spontaneous IgG-, IgM-, and IgA-PFC in PBL of 26 patients with classical erosive RA receiving either gold salts or D-penicillamine were similar to those observed in 20 healthy controls. In contrast, significantly higher numbers of IgG- and IgA-PFC, but not IgM-PFC, were found in PBL of nine patients with classical erosive RA receiving non-steroidal anti-inflammatory drugs (NSAID) alone. Furthermore, spontaneous PFC in SFL from 16 consecutive patients with RA receiving second-line drugs, as well as 17 patients with other forms of arthritis (non-RA) were generally low and significantly less than those observed in 20 RA patients on NSAID alone. Moreover, a wide individual variation in PFC, especially in relation to the IgG class, was recorded in the synovial lymphocytes. These studies imply that treatment with second-line drugs is associated with normalisation of B cell activity in RA patients, and that the effect can be detected at the cellular level both in blood and synovial fluid.

Neoplasms of the immune system in rheumatoid arthritis

Two studies are reported of patients with rheumatoid arthritis. The first was a retrospective-prospective-prospective study and comprised a cohort of 489 patients with rheumatoid arthritis followed for a mean of 12.2 years. Lymphoproliferative malignancies developed in 10 patients (2.2 percent) after a mean interval of 11.8 years. The second was a study of 30 patients, from various centers in England, with rheumatoid arthritis and lymphoproliferative malignancies. The effects of chronicity of rheumatoid arthritis, drug therapy, and possible predisposing factors in the etiology of the lymphoproliferative malignancies were examined. Cytotoxic drugs could not be implicated in the pathogenesis of the lymphoproliferative malignancies, but phenylbutazone and D-penicillamine may have played a role in some cases. Current evidence supports the hypothesis that chronic synovitis in rheumatoid arthritis is associated with persistent activation of lymphocytes in lymph nodes and eventual malignant transformation in some cases.

Cryoglobulins in cases of rheumatoid arthritis

Clinically diagnosed cases with different grades of rheumatoid arthritis (RA) were studied for (a) cryoglobulin content (b) constituents of cryoglobulins, and (c) rheumatoid factor (RF) titers in sera and cryoglobulins. Of 60 patients, 28 (46.66%) had significantly high levels of cryoglobulins and were mainly distributed in the severe group. Significant amounts of IgG and IgM were found in the cryoglobulins of the 15 cases of RA studied. Ten of these cases had detectable C3 in their cryoglobulins. Of 20 cases of RA, 10 had detectable levels of RF in their cryoglobulins, as shown by the latex agglutination method. There was no significant correlation between the RF titers of cryoglobulins and the RF titers in the corresponding sera or the quantity of IgM and IgG components in them. Since the RF titer in cryoglobulin seemed to indicate the severity of the disease, the use of this parameter is proposed for diagnosis and prognosis of RA.

Serum immunoglobulins in patients with chronic tonsillitis

Serum immunoglobulin (IgG, IgA and IgM) levels were determined in patients with chronic tonsillitis before and one month after tonsillectomy. The preoperative levels of serum IgG, IgA and IgM were significantly higher when compared with the controls. The increase may be due to repeated antigenic stimulation. The post-operative levels for the three immunoglobulins were decreased; however, a significant reduction was observed for IgG only where the mean value was comparable with the control group. The data confirm that tonsillectomy does not disturb the humoral immune system of the body.

Increased serum IgG levels in essential hypertension

Serum IgG levels were significantly increased (P less than 0.001) in 33 (20 male and 13 female) essential hypertensive cases (mean = 2083.87 +/- 99.94 mg/dl) when compared to 30 (15 male and 15 female) random normotensive control subjects (mean = 993.84 +/- 72.25 mg/dl). Of the 33 cases, 12 (36.3%) were familial and the rest were sporadic. No significant difference was observed in the IgG levels between familial and sporadic cases. Similarly, no significant difference was found between male and female hypertensive patients both in the familial and the sporadic group or between smokers and non-smokers. However, the levels of IgG were found to be increased in the initial stages of onset of the condition (duration of less than 1 yr). The present study supports the probable involvement of immunological responses in essential hypertension.

Thrombocytosis of active rheumatoid disease

Two cross-sectional and one longitudinal study of patients with rheumatoid arthritis showed that platelet number correlated with both clinical and laboratory parameters of disease activity, including erythrocyte sedimentation rate, zeta sedimentation ratio, viscosity of plasma and blood, white cell count, liver enzymes, rheumatoid factor, and several acute-phase proteins. There was also an inverse relationship between platelet number and the haemoglobin and serum albumin levels. III Indium-labelled platelet survival was reduced in 4 patients with active rheumatoid arthritis despite a raised platelet count, with labelled platelets being localised to inflamed joints in the 2 patients studied. Platelet aggregation was normal. We suggest that the raised platelet count of active rheumatoid arthritis may be a useful index of disease activity and may represent a bone marrow stress (syndrome) response to shortened platelet survival, with platelet sequestration occurring in areas of synovial inflammation.

Discriminatory indices of response of patients with rheumatoid arthritis treated with D-penicillamine

A long-term study is being undertaken to classify drugs used as specific agents in the treatment of rheumatoid arthritis in terms of their effects on biochemical and clinical characteristics of the disease. In particular is hoped to establish those indices which are most relevant to the response of RA to treatment. Fifteen patients were treated with D-penicillamine after an initial period of 2 weeks on aspirin alone, when the baseline investigations were made. The dose of penicillamine was increased gradually to a maximum of 500 mg a day over the period of 6 months, and changes in 8 clinical and 25 laboratory indices were measured on 8 separate occasions in the 6-month period. Marked clinical improvement took place, and this was mirrored by changes in a wide range of biochemical parametaers. ESR and C-reactive protein were shown to be the most suitable indices of disease improvement with penicillamine treatment.

Plasma protein patterns in health and disease

The complex nature of protein metabolism has made interpretation of serum protein data a difficult task. Interpretive efforts can be facilitated by use of protein profiles which consist of quantitative immunochemical data combined with qualitative electrophoretic patterns. These profiles can be designed to clarify physiological relationships and emphasize pathological conditions through pattern recognition. This review will present protein profiles observed in acute, subacute, and chronic inflammation: liver diseases, protein losing disorders, plasma cell dyscrasias, humoral immune deficiencies, autoimmune diseases, genetic deficiency states, and other disorders. The value of consultative interaction and the use of combined profiles in the assessment of a patient's protein status will be covered. A discussion of protein patterns in normal individuals will include data on day-to-day, age- and sex-related variation. A section on management of protein data will present various approaches to profile reporting. Graphical report formats which minimize the time required for information transfer and simplify assimilation of results will be emphasized.

Chrysotherapy. Suppression of immunoglobulin synthesis

Forty-four subjects with classic or definite rheumatoid arthritis who were on individualized chrysotherapy were observed for changes in serum protein electrophoresis, immunoglobulins, and circulating lymphocyte counts. By paired variate analysis, significant declines from pretreatment values were recorded for the following--electrophoretic protein fractions: gamma, alpha-1, alpha-2, (P less than 0.05); immunoglobulins: IgM--53% (P less than 0.001), IgG--37% (P less than 0.01), IgA--34% (P less than 0.001). Rheumatoid factor decreased in 29 of 39 subjects, 15 becoming seronegative (P less than 0.001); circulating lymphocytes decreased by 27% (P less than 0.001). The maximal suppressive effect on IgG and IgM was not achieved until the third and fourth years of therapy by sustained weekly administration of gold sodium thiomalate (one year cumulative dosage, mean 2106 mg, range 1065-2,885; greater than or equal to 4 year cumulative dosage, mean 8747 mg, range 5,385-15,160 mg). An immunosuppressive effect is suggested by these results.

Assessment of rheumatoid activity based on clinical features and blood and synovial fluid analysis

Joint inflammation in rheumatoid arthritis has been assessed, and the most useful guides to disease activity were determined by analysis of synovial fluid and blood together with the history of joint disability. The patient's own evaluation of the amount of pain suffered was the most useful clinical assessment. Differential cell count and glucose estimations were the most helpful guides in the synovial fluid, while C-reactive protein in the serum most accurately reflected disease activity. The effects of systemic steroids on these indices were studied, and the differences between seronegative and seropositive patients noted.

Effects of therapeutically useful thiols (DL-penicillamine and alpha-mercaptopropionylglycine) on immunoglobulins

The action of 0·05 M DL-penicillamine (DL-P) and α-mercaptopropionylglycine upon immunoglobulins, both in their native serum and after isolation, has been studied.

IgM was always affected, apparently with breakdown of 19S polymers and release of 7S sub-units. This depolymerization leads both to a change in electrophoretic mobility and to increased diffusibility in gels, as well as to decrease in serum viscosity.

IgG, as a rule, is not affected when studied in whole serum. The exception to the rule is provided by monoclonal proteins of the IgG3 subgroup. The observed effects are variable, and may consist of an increase in the electropositivity of the molecules, the release of light chains, or the splitting into Fab- and Fc-like fragments.

IgA was irregularly affected. The results suggest that several types of action may be present: depolymerization of high molecular weight polymers, which seem to be more resistant to the action of DL-P than its IgM counterparts, unfolding of 7S molecules with increased electropositivity, and breakdown of 7S molecules into halves, each containing both H and L chains.

Precipitation of cryoglobulins was inhibited by both thiols, both when added to whole serum or isolated proteins.

Raised serum IgG levels in hypertension

Serum IgG levels were significantly higher in 118 severely hypertensive patients compared with a group of 163 normotensive blood donors, matched for age and sex. Serum IgA and IgM were the same in both groups. Raised levels of serum IgG were found in patients who had never been treated for hypertension, as well as in those who were treated with methyldopa or other hypotensive drugs.It is suggested that the raised levels of serum IgG may be an index of vascular damage induced by hypertension.

Altered immunoglobulin metabolism in systemic lupus erythematosus and heumatoid arthritis

IgG and IgM metabolism was evaluated in 10 patients with systemic lupus erythematosus (SLE), 10 patients with rheumatoid arthritis (RA), and in seven normal volunteers. The biological half-lives of purified IgG and IgM, labeled with (131)I and (125)I, respectively, were determined by serial measurements of radioactivity in the blood and urine with a gamma well counter, and by serial counts of total body radioactivity in a total body counting chamber. The mean survival half-life for IgG in patients with SLE was 8.2 days as compared to an average of 18 days in normal controls. An average of 10.1% of total body IgG was catabolized daily compared to a mean of 3.9% in normal controls. Turnover of IgM in patients with SLE was, with very few exceptions, normal. In contrast, patients with rheumatoid arthritis revealed a milder abnormality of IgG metabolism, but markedly abnormal IgM catabolism with a mean half-life averaging 5.9 days as compared to 9.3 days in control subjects. An average of 14.2% of total body IgM was catabolized daily in patients with RA as compared to 8.1% in normal controls. Our data suggest that there are basic differences between patients with RA and SLE in the synthesis and catabolism of IgG and IgM not readily apparent from serum IgG and IgM concentration. Abnormal IgG and IgM metabolism may be related to underlying immunological mechanisms in these diseases. Immunoglobulin turnover studies appear to be an additional means for the characterization of rheumatic diseases.