Precipitating Auto-Antibodies in the Connective Tissue Diseases

Abstract

Specimens of serum from 188 patients with connective tissue diseases and from 353 "control" patients were examined by an agar-diffusion technique for the presence of factors reacting to give precipitation with saline extracts of various human tissues. Precipitation was observed with 57 of the test serum specimens and with eight of the controls. The precipitating titers of positive specimens ranged up to 1 in 512. Comparative tests upon the positive specimens showed the occurrence among them of several precipitating factors. Four of these were investigated further, and evidence is presented that they are autoantibodies which react with normal cellular constituents. One of the four cellular constituents concerned is considered to be deoxyribonucleic acid (DNA); the other three remain unidentified. The incidence of the four antibodies provides further links between the various types of connective tissue disease. At the same time, individual connective tissue diseases tend to be associated with particular antibodies. Precipitating factors were detected in the serum of "control" patients with "para- globulinemia", chronic thyroiditis, liver disease, aplastic anemia, and sarcoidosis. The results of precipitin tests are compared with those described by workers using Gadjusek''s "auto-immune complement-fixation reaction" (AlCF), and an explanation of negative autologous tests reported with this latter technique is suggested.