Clinical and serological aspects of patients with anti-Jo-1 antibodies an evolving spectrum of disease manifestations

The aim of this study was to compare ELISA, immunodiffusion and immunoblot for the detection of anti-Jo-1 antibodies, and to investigate the associati on of the results with clinical manifestations. In two medical centres for rheumatology and one for pulmonologoy, all patients with suspected connecti ve tissue disease were screened over a 5-year period for anti-Jo-1 antibodi es by ELISA. Positive sera were controlled in another laboratory by immunod iffusion. If immunodiffusion was negative, sera were controlled again by EL ISA. ELISA-positive immunodiffusion-negative sera were tested by immunoblot ting. The patients were characterised clinically, and their clinical signs and symptoms were compared with those of 257 patients with anti-Jo-1 antibo dies published in 15 case series and 30 case reports. Twenty-five patients had a positive ELISA test. Fifteen sera were positive by ELISA and immunodi ffusion (group 1). Three sera showed high titres in both ELISA tests with n egative immunodiffusion and immunoblot (group 2). Seven sera showed low tit res in both ELISA tests. The results were negative in the other tests (grou p 3). Patients in groups 1 and 2 could be classified as Jo-1 syndrome patie nts. Of these 18 patients, 15 had arthritis, 14 had myositis and 14 had int erstitial lung disease. Only four patients had myositis at disease onset. W e describe four unusual patients with Jo-1 syndrome in detail: 1. Long hist ory of seronegative rheumatoid arthritis; 2. Sjogren's syndrome with Ro- an d La-antibodies; 3. Scleroderma and bronchial carcinoma with centromere ant ibodies; 4. Corticoid-sensitive psychosis. Patients with suspected connecti ve tissue disease may be screened for anti-Jo-1 antibodies by ELISA. It det ects some patients that are missed by immunodiffusion. Especially lower ELI SA titres should be controlled by another method because of the low specifi city of the test. The clinical picture is variable. Most patients have feat ures other than myositis at disease onset.