Studies on immune complexes

Thyroid Dysfunction in Ménière's Disease: A Comprehensive Review

INTRODUCTION

The precise etiology of Ménière's disease (MD) remains unknown; however, given the association of MD with serum antibodies and human leukocyte antigen (HLA) complex, several studies have proposed a relationship between MD and thyroid disorders. Similarly, multiple hypotheses exist regarding the metabolic disturbances of fluctuating thyroid hormone as a potential contributing agent in the development of MD.

METHODS

A total of 171 abstracts were identified and screened by 2 independent reviewers. Based on inclusion and exclusion criteria, 8 studies were selected for final analysis. Due to heterogeneity of clinical data, meta-analysis was not feasible.

RESULTS

The prevalence of autoimmune thyroid disease and hypothyroidism in MD varied significantly from 1 to 38%. Notable bias was introduced given the lack of standardization of diagnostic criteria across studies. Articles that described autoimmune thyroid-specific antibodies and HLA types also presented inconclusive results. Multiple studies noted a potential etiologic role of hypothyroidism in MD, which was often confounded by thyroxine supplementation.

CONCLUSIONS

Despite a potential correlation in the medical literature between thyroid disorders and MD, there is currently no definitive causal relationship. Although most of the present medical literature focuses on autoimmunity, dysregulated thyroid hormone levels may also be implicated in the association of MD with thyroid disorders.

C3-containing serum immune complexes in patients with systemic lupus erythematosus: correlation to disease activity and comparison with other rheumatic diseases

Although testing for circulating immune complexes (CIC) is regarded as a useful, complementary, laboratory parameter in the differential diagnosis and management of immune complex-induced vasculitis syndromes, there is still an uncertainty with regard to assay systems used for the demonstrated of soluble immune complexes. This is partly due to difficulties in the reproducibility, handling and principle limitations of available test systems for the assessment of soluble immune complexes in body fluids. In the present communication a modification of the anti-C3 test for the determination of CIC was developed using nitrocellulose as a solid phase matrix. IgG-, IgA- and IgM-containing CIC were determined and quantified using standard immune complex preparations. When 39 sera of SLE patients, 12 sera of patients with vasculitis syndromes, 10 sera of rheumatoid arthritis patients and 11 sera of patients with ankylosing spondylitis were tested, predominantly IgG-containing CIC could be demonstrated. Only in SLE patients was a significant amount of other immunoglobulin isotypes detected in CIC. In these patients a significant difference of IgG-containing CIC levels was found with regard to patients with high and low disease activity (P less than 0.0001). A significant correlation was also established between IgG-containing CIC and anti-dsDNA antibodies (P less than 0.001). In a longitudinal study the isotypes in the isolated CIC were found to be constant.

Immune complex assays: diagnostic and clinical application

The presence of circulating immune complexes have been described in many different human disease states but the significance of their presence has always been a subject for debate. Improvements in the methods of detecting immune complexes have demonstrated a wide degree of heterogeneity, which accounts for the difficulty in obtaining accurate and reproducible measurements, even in the same individual. Techniques for isolating individual complexes, characterizing their pathophysiological properties, and biochemically analyzing the nature of the complexed antigen are now being used to provide data that is helping to clarify the role of immune complexes in the pathogenesis of disease. In addition, such studies are also providing data which is proving that immune complexes have a potential role in immune regulation.

Immune status in patients with Menière's disease

Sera of 164 patients with classical Meniere's disease were screened for autoantibodies, immune complexes and HLA status. Increased thyroid microsomal antibodies were significant in those patients in the 40- to 60-year age range. Raised IgM complexes and C1q component of complement were significant in all age groups. Low levels of IgA complexes were a consistent finding and were significantly lower in the HLA Cw7 group. Patients with migraine had no increased incidence of immune disturbances.

Cyclophosphamide treatment in polyarteritis nodosa

Five male patients with polyarteritis nodosa were treated with cyclophosphamide as follows: 3 mg/Kg/die i.v. up to maximum of 3 g.; subsequently, 200 mg/die per os for two weeks, then 100 mg per os every other day for three months; finally, 100 mg every fourth day until the 18th month. One patient, who also had fever, received 25 mg/die of prednisone for the initial three weeks of treatment. Before treatment ESR, WBC, and circulating immune-complexes were increased, while C3a, C3c and C4 serum complement components levels were normal. Skin ulcers healed within 4 months. A progressive marked improvement of visceral damages in the first months of therapy have been noted (e.g. blood pressure values in normal range after suspension of concomitant antihypertensive treatment, regression of peripheral neuropathy, etc. etc.). No further ischemic lesions occurred during treatment. Significant decreases of ESR and serum immune-complexes levels were detected. No untoward effects due to cyclophosphamide were observed. These findings support the effectiveness of this drug in polyarteritis. The possibility of association with glucocorticoids during the acute phase of disease is also discussed.

Interstitial lung disease in scleroderma. Immune complexes in sera and bronchoalveolar lavage fluid

Interstitial lung disease is a common feature of scleroderma (systemic sclerosis), and it may be a major determinant of morbidity and mortality. Analysis of bronchoalveolar lavage fluid from patients with scleroderma has shown evidence of inflammation in the lower respiratory tract of many patients. We have analyzed sera and bronchoalveolar lavage fluid from scleroderma patients for the presence of immune complexes, which may play a role in the inflammatory process. Using a solid-phase C1q enzyme-linked immunosorbent assay, we detected immune complexes in the sera of 6 of 23 patients (26%) and in none of 32 controls (P less than 0.01). All 6 patients with serum immune complexes had inflammatory cells in bronchoalveolar lavage fluid, and the presence of serum immune complexes correlated with the percentage of neutrophils in lavage fluid (P less than 0.02). Immune complexes were detected in lavage fluid of 11 of 21 patients (52%) compared with 1 of 7 normal controls (14%). Subjects having immune complexes in lavage fluid had a lower forced vital capacity than did those without lavage fluid immune complexes (P less than 0.05). The levels of immune complexes in bronchoalveolar lavage fluid exceeded those in serum by a mean of 45-fold, suggesting either local formation or selective deposition of immune complexes in the lower respiratory tract of some scleroderma patients.

Detection and quantitation of circulating immune complexes in arterial blood of patients with rheumatic disease

We developed antigen-nonspecific enzyme-linked immunoassays (ELISA) to quantitate IgG-C3- and IgM-C3-containing circulating immune complexes (CIC) in venous and arterial blood from rheumatic disease patients. Standards were diethylaminoethyl (DEAE)-purified, heat-aggregated IgG incubated with fresh human serum (for IgG-C3 CIC) and IgM rheumatoid factor-rich serum incubated with reduced, alkylated IgG and then with fresh human serum (for IgM-IgG-C3 CIC). Venous serum and plasma IgG-C3 and IgM-C3 CIC correlated closely (P less than 0.01). Rheumatoid arthritis (RA) and systemic lupus erythematous (SLE) patients had elevated levels of venous IgM-C3 CIC (P less than 0.0001) but not IgG-C3 CIC; patients with vasculitis, inflammatory rheumatic diseases, or noninflammatory rheumatic diseases had mean values similar to normal individuals. Venous IgG-C3 and IgM-C3 CIC did not correlate. Paired venous and arterial samples from 16 rheumatic disease patients averaged comparable amounts of IgG-C3 and IgM-C3 CIC, respectively; venous and arterial IgM-C3 CIC levels in patients significantly exceeded normals (P less than 0.05). Venous and arterial IgG-C3 CIC levels correlated closely (P less than 0.01) as did venous and arterial IgM-C3 levels (P less than 0.05). Thus, arterial CIC offered no advantage over venous determinations for rheumatic disease patients. IgM-C3 CIC were elevated in patients with RA and SLE when IgG-C3 CIC were not. Ig isotype-specific CIC quantitation may be useful for certain rheumatic diseases.

Circulating immune complexes and rheumatoid arthritis: a comparison of different assay methods and their early predictive value for disease activity and outcome

The performance of four different assays for circulating immune complexes-the C1q solid phase method, one using protein A and one using anti-IgG, C1q PEG, and the 2% PEG method-were compared in 61 patients with early rheumatoid arthritis followed up for two years. There were weak but statistically significant correlations between the results from some of the pairs of assays, but the changes over time from any single assay did not correlate with those from any of the other assays. None of the assays predicted either future disease activity, as measured by subsequent ESR, CRP, and articular index; or functional outcome, as measured by wrist extension, Steinbocker functional capacity, and the Stanford health assessment questionnaire. It is unlikely therefore that the measurement of immune complexes is of value in predicting early outcome in patients with rheumatoid arthritis.

Immune Complex-Associated Deafness: Preliminary Communication

During the last year patients presenting with progressive bilateral or sudden sensorineural deafness of unknown aetiology have been investigated for possible abnormal immune activity. Twenty-six cases are reported in which significantly raised circulating immune complexes were present, together with 2 cases of clinical autoimmune deafness where the complexes were normal. Thirty-six control subjects were also studied. Following a review of the clinical features, the pathogenesis of this new association with sensorineural deafness is discussed. In some cases the aetiology is probably autoimmune, and in others related to infection. In certain patients the deafness has been partly reversed by medical treatment with systemic steroids or plasma exchange. It is hypothesized that circulating immune complexes may reflect a previously unrecognized final common pathophysiological pathway in a variety of cochleovestibular disorders.

Evaluation of plasma C3d and immune complex determinations in the assessment of disease activity of patients with rheumatoid arthritis, systemic lupus erythematosus, and spondylitis ancylopoetica

Patients with rheumatoid arthritis, systemic lupus erythematosus, and spondylitis ancylopoetica were examined, along with healthy controls, for C3d plasma levels, circulating immune complexes, C3 serum levels, and CRP. Immune complexes were determined using a Clq binding assay, a 2.75% PEG precipitation technique, including the analysis of IgG and C3, and a new laser nephelometric latex test. C3d plasma levels were significantly (P less than 1%) elevated in all groups of patients as compared to controls. With regard to the demonstration of circulating immune complexes, the PEG precipitation method discriminated best between patients and the control population. It was not possible to differentiate between the different disease entities with neither C3d serum levels or immune complexes. Concerning the assessment of disease activity, none of the evaluated parameters alone appears to be of clinical relevance. The individual application of more than one immune complex assay in combination with the measurement of C3d serum levels must be recommended if disease activity is to be assessed.

Decrease of the OKT8 positive T cell subset in polymyalgia rheumatica. Lack of correlation with disease activity

Peripheral T cell populations were investigated in 35 patients suffering from polymyalgia rheumatica. The total number of T cells was low compared with those of a control group of similar age (P less than 10(-3). This decrease was demonstrated by using both classic E-rosette and monoclonal antibody techniques (OKT3, and OKT4 + OKT8) and was shown to be secondary to a selective T8 defect (P less than 10(-9). There was no correlation between the decrease in T8 (a cytotoxic suppressor T cell subset) and steroid therapy, disease activity, and temporal arteritis, nor between this decrease and the T gamma percentage and the presence of circulating immune complexes (CIC). The T gamma cell percentage was low in the patient group (P less than 10(-5) and correlated with the presence of detectable CIC (P less than 0.05). In contrast to the T8 and T gamma defects, concanavalin A-stimulated cells from 5 selected patients were found capable of suppressing in vitro anti-trinitrophenyl response. This suppression was found in both autologous and allogeneic experiments. From these data one can assume that an immune anomaly (T8 defect) could be the origin of CIC and the disease occurrence.