The Use of Immunoblotting to Detect Antibodies to Nuclear and Cytoplasmic Antigens

Using the immunoblotting technique, sera from 433 patients with rheumatic diseases were screened for the presence of antibodies against several nuclear and cytoplasmic antigens, such as RNP, Sm, Ro(SSA), La(SSB), CR-19 (centromeric antigen), Topo-1 (Scl-70), Jo-1, histone and 56 kD. At the same time clinical data from these patients were collected without prior knowledge of the immunoblotting results. Syndrome-specific autoantibodies were found for mixed connective tissue disease (antibodies against the RNP related 70 kD antigen), for CREST (anti-CR-19 antibodies), for diffuse scleroderma (anti-Topo-1 antibodies) and for polymyositis (anti-Jo-1 antibodies). Almost all specific autoantibodies were present exclusively in patients with a connective tissue disease. Controls were only in a few cases positive for antihistone and anti-56 kD antibodies. Associations of specific autoantibodies with clinical and laboratory features of the patients were mostly as expected. However, some unexpected associations were found, for example polymyositis and calcinosis with anti-Sm antibodies, sicca symptoms with anti-centromere antibodies and leucopenia with Ro(SSA) and La(SSB).