Gordon C. Sharp

Mixed connective tissue disease-an apparently distinct rheumatic disease syndrome associated with a specific antibody to an extractable nuclear antigen (ENA)

Abstract We describe the clinical and serologic findings in twenty-five patients with an apparently distinct rheumatic disease syndrome which we have termed mixed connective tissue disease. All these patients had hemagglutinating antibody to an extractable nuclear antigen (ENA) which consists mainly of protein and ribonucleic acid (RNA). A marked sensitivity of the hemagglutination antigen to ribonuclease indicated that the specificity of the antibody to ENA circulating in these patients was different from that of antibody to ENA which occurred in about 50 per cent of the patients with systemic lupus erythematosus. Serum from patients with mixed connective tissue disease also contained high titers of speckled pattern fluorescent antinuclear antibody which showed the same response of tissue antigens to enzyme digestion as found with hemagglutinating antibody. There was no detectable Sm antibody. Antibody to native deoxyribonucleic acid (DNA) was infrequent and of low titer, and serum complement levels were normal or elevated. The clinical characteristics of the patients with mixed connective tissue disease included a combination of features similar to those of systemic lupus erythematosus, scleroderma and polymyositis. Most of these abnormalities were responsive to corticosteroid therapy. Thus, the detection of antibody to ENA with a well defined specificity allows recognition of an apparently distinct mixed connective tissue disease syndrome which is characterized by an excellent response to corticosteroid therapy and a favorable prognosis.

Association of Antibodies to Ribonucleoprotein and Sm Antigens with Mixed Connective-Tissue Disease, Systemic Lupus Erythematosus and Other Rheumatic Diseases

Extractable nuclear antigen contains ribo-nuclease-sensitive (ribonucleoprotein) and ribonuclease-resistant (Sm) components. To determine the diagnostic usefulness of antibodies to these antigens, a multicenter study was undertaken in which serums were analyzed for these antibodies and the findings compared with clinical and other laboratory characteristics of the patients. Of 100 patients with hemagglutinating antibodies to ribonuclease-sensitive extractable nuclear antigen, and only the same antibodies by immunodiffusion, 74 per cent had typical features of mixed connective-tissue disease; 12 features of systemic lupus erythematosus, eight those of scleroderma and six an undifferentiated mild connective-tissue disease. Of 27 patients with hemagglutinating antibodies to ribonuclease-resistant extractable nuclear antigen (and Sm antibodies by immunodiffusion), 85 per cent had typical systemic lupus. Thus, antibodies to nuclear ribonucleoprotein and Sm are of diagnostic use; if the serum contains only ribonucleoprotein antibody in high titer, it is likely that the patient has mixed connective-tissue disease.

Association of autoantibodies to different nuclear antigens with clinical patterns of rheumatic disease and responsiveness to therapy

Using a hemagglutination test which can detect antibodies to (a) native and denatured deoxyribonucleic acid (DNA) and (b) an extractable nuclear antigen (ENA), a comparative study of patterns of autoantibody formation has been done in systemic lupus erythematosus (SLE) and related rheumatic diseases. Antibody to native DNA was present in the serum in 96% of patients with active SLE and disappeared during remissions. Antibody to ENA was found in 86% of those patients with SLE nephritis who responded to treatment but in only 8% of those who did not. The highest titers of antibody to ENA were found in patients having a mixed connective tissue disease syndrome with features of SLE, scleroderma, and myositis. The latter syndrome was notable for the absence of renal disease and for a striking responsiveness to corticosteroid therapy. Hemagglutination testing of 277 sera from normal persons and patients with a wide variety of acute diseases other than SLE revealed the presence of antibody to native DNA in only 1.4% and antibody to ENA in only 0.4%. These results yield significant correlations among the pattern of autoimmune reactivity, the clinical form of the rheumatic disease, and responsiveness to treatment. They implicate the qualitative nature of the patients immune response as a conditioning factor in the type of disease. Together with other correlations they may allow classification of rheumatic diseases into more biologically meaningful groups and lead to more selective methods of therapy.

Antibodies to a nuclear/nucleolar antigen in patients with polymyositis overlap syndromes

A precipitating antigen-antibody system has been characterized that occurs in patients with polymyositis. At least half of the patients not only have polymyositis but also have scleroderma. The proposed name for this antigen found in calf thymus extract (CTE) is PM-Scl, to indicate the almost universal presence of polymyositis and the frequent occurrence of scleroderma in the patients who make antibodies to this antigen. The antigen is probably nucleolar since all sera which precipitate with the PM-Scl antigen stain the nucleoli of Hep2 cells by indirect immunofluorescence. The PM-Scl immune system is a distinctive one different from the other known precipitins that occur in patients with polymyositis and dermatomyositis including Jo1, nRNP, and Mi. This PM-Scl antigen and its antibody represent one system which constitutes part of the reactions previously designated as PM1. Interlaboratory exchange of sera and extracts have established the unique nature of this reaction which occurs in patients with inflammatory myopathy.

Immune responses to hydralazine and nuclear antigens in hydralazine-induced lupus erythematosus.

Abstract Immune responses to hydralazine were detected in patients with hydralazine-induced lupus but not in patients taking hydralazine without developing toxicity, patients with systemic lupus er...

Gastrointestinal Manifestations of Mixed Connective Tissue Disease

We examined the gastrointestinal tract abnormalities in 61 patients with mixed connective tissue disease. The first 34 were part of a prospective longitudinal study that included manometric and radiographic evaluation of the esophagus. Heartburn (48%) and dysphagia (38%) were by far the most common gastrointestinal symptoms. Seventeen percent of patients undergoing manometry had distal esophageal aperistalsis, and 43% low-amplitude peristalsis (less than 30 mmHg). Studies in 10 patients before and after treatment suggested that esophageal dysfunction in mixed connective tissue disease may be responsive to corticosteroids. Upper esophageal sphincter hypotension was also common. One patient had marked upper esophageal sphincter hypotension and recurrent aspiration, which resolved with corticosteroid therapy. Findings on radiographic studies of the stomach and small bowel in 54 patients and barium enemas in 16 patients were reviewed. Our series included one case each of malabsorption, colonic and small bowel perforations due to vasculitis, chronic active hepatitis, and acute pancreatitis. In conclusion, any area of the gastrointestinal tract may be affected by mixed connective tissue disease, although the esophagus is the most common location. The gastrointestinal aspects of mixed connective tissue disease overlap with those of progressive systemic sclerosis, polymyositis, and systemic lupus erythematosus.

Acute and long-term effects of nifedipine on pulmonary and systemic hemodynamics in patients with pulmonary hypertension associated with diffuse systemic sclerosis, the CREST syndrome and mixed connective tissue disease.

Ten patients with pulmonary hypertension associated with diffuse systemic sclerosis (1 patient), the CREST syndrome (calcinosis cutis, Reynauds phenomenon, esophageal dysmotility, sclerodactyl, telangiectasia) (6 patients) and mixed connective tissue disease (3 patients) were studied to assess the effect of oral nifedipine on pulmonary and systemic hemodynamics. Each patient underwent right-sided cardiac catheterization just before nifedipine administration. Thereafter, oral nifedipine was administered in 10 mg increments every 90 minutes until pulmonary vascular resistance normalized or a total dose of 30 mg was achieved. Hemodynamic measurements were obtained at 30-minute intervals for 3 hours, then hourly for 9 hours (acute study). Hemodynamic studies were repeated 3 to 6 months after the initial catheterization with the minimum dose of oral nifedipine (administered every 8 hours) required to achieve maximal reduction of pulmonary vascular resistance in the acute study (long-term study). In the acute study, oral nifedipine produced a significant decrease in mean pulmonary vascular resistance from 6.3 +/- 3.8 to 4.3 +/- 3.6 U (p less than 0.001). Similar changes in pulmonary vascular resistance were noted in the long-term study (n = 6). The results indicate that oral nifedipine is capable of producing an acute and sustained reduction in pulmonary vascular resistance in patients with pulmonary hypertension associated with diffuse systemic sclerosis, the CREST syndrome and mixed connective tissue disease.

Prolactin levels and antinuclear antibody profiles in women tested for connective tissue disease.

Hyperprolactinemia has been reported in some patients with active systemic lupus erythe matosus (SLE). To determine if there was an association between selected autoantibodies and hyperprolactinemia, we assayed prolactin concentrations in sera from women sub mitted to a reference antinuclear antibody laboratory. Autoantibody-positive samples were separated into groups that contained antibodies to double-stranded DNA (anti-DNA), anti bodies to SSA/Ro (anti-SSA/Ro), or antibodies to both SSA/Ro and SSB/La (anti-SSA/Ro- SSB/La). Results were compared with autoantibody-negative sera from age-matched women, submitted to the same laboratory. We also compared the study groups with a separate cohort of 84 healthy women who were not referred for autoantibody testing. Elevated prolactin levels were clustered in 20% of sera from anti-DNA-positive women ≤50 years of age. Twenty-one percent of anti-SSA/Ro-SSB/La-positive women < 50 years of age were hyperprolactinemic. Four of the 15 hyperprolactinemic women identified in this survey had no known cause of elevated prolactin. In the other 11 individuals, secondary causes such as hypothyroidism, pregnancy, chronic renal failure, and medications may have accounted for high serum prolactin values. We also examined sera by Western blot, to determine if immunoblot patterns were associated with elevated serum prolactin concentra tions. The hyperprolactinemic sera yielded novel bands migrating at 70 kd, 32 kd, and 16.5 kd. This study confirmed the reported associations of hyperprolactinemia with SLE and Sjögrens syndrome. Multiple factors appeared to contribute to elevated serum prolactin levels in women with connective tissue diseases, and the presence of hyperprolactinemia was related to unique findings on immunoblot analysis.Sjögrens syndrome (SS) is a chronic autoimmune rheumatic disorder characterized by lymphocytic infiltration and destruction of exocrine glands, mainly of salivary and lacrimal glands, leading to dryness of mouth and eyes. It can occur either alone (primary SS) or in association with almost every systemic autoimmune rheumatic SS). Usually, SS patients have slowly progressive disease confined in exocrine glands, however, in approximately one third of primary SS patients the disorder presents a systemic and progressive course with involvement of diverse extraglandular sites and in a small but significant number of patients with lymphoid neoplasia development. Although the aetiology of SS remains unknown, chronic immune system stimulation is thought to play a central role in the pathogenesis of the disorder, as illustrated by several indices of immunological hyperactivity, including various autoantibodies, polyclonal hypergammaglobulinemia and circulating paraproteins. To date, treatment of SS remains largely empirical and symptomatic, and no clinical trial has been proved capable to change the course of the disease. Hydroxychloroquine has been successfully applied for the treatment of arthralgias, myalgias and general constitutive symptoms of SS patients. In an initial small open study, hydroxychloroquine administration has been shown to improve features of immunological hyperreactivity, such as hypergammaglobulinaemia and autoantibody levels. However, large prospective double-blind studies are still needed to assess the long-term efficacy of hydroxychloroquine in preventing extraglandular involvement and lymphoma development in primary SS patients.

Dual Roles for IFN-γ, But Not for IL-4, in Spontaneous Autoimmune Thyroiditis in NOD.H-2h4 Mice

Spontaneous autoimmune thyroiditis (SAT) is an organ-specific autoimmune disease characterized by chronic inflammation of the thyroid by T and B lymphocytes. To investigate the roles of Th1 and Th2 cytokines in the pathogenesis of SAT, IFN-γ−/− and IL-4−/− NOD.H-2h4 mice were generated. IL-4−/− mice developed lymphocytic SAT (L-SAT) comparable to that of wild-type (WT) mice. They produced little anti-mouse thyroglobulin (MTg) IgG1, but had levels of anti-MTg IgG2b comparable to WT mice. Compared with WT mice, IFN-γ−/− mice produced significantly less anti-MTg IgG1 and IgG2b. Absence of IFN-γ resulted in abnormal proliferation of thyroid epithelial cells with minimal lymphocyte infiltration. Thyroids of IFN-γ−/− mice had markedly reduced B lymphocyte chemoattractant expression, B cell and plasma cell infiltration, and decreased MHC class II expression on thyrocytes compared with WT mice. Adoptive transfer of WT splenocytes to IFN-γ−/− mice restored the capacity to develop typical L-SAT, enhanced anti-MTg IgG1 and IgG2b production, up-regulated MHC class II expression on thyrocytes and decreased thyrocyte proliferation. These results suggest that IFN-γ plays a dual role in the development of SAT. IFN-γ is required for development of L-SAT, and it also functions to inhibit thyroid epithelial cell proliferation.

Current concepts in the classification of connective tissue diseases. Overlap syndromes and mixed connective tissue disease (MCTD).

New principles are discussed for the classification of the diffuse collagen diseases, particularly the mixed connective tissue disease (MCTD), with clinical and historical explanation. Emphasis in classification has shifted from a concern with tissue pathology to serologic anomalies, which may involve eleven different antigens, many from human cell nuclei. New serologic tests, such as the ribonucleoprotein (RNP) antibody test, may be superior to the well-known fluorescent antinuclear antibody (ANA) studies for diagnosis and follow-up of diffuse collagen diseases. Functional clinical studies, such as esophageal motility, gas exchange in the lung, and major joint mobility, which may appear early in MCTD, are more important to diagnosis than anatomic studies of late-developing lesions.