Heterogeneity of intracellular antigens for determination of autoantibodies in patients with systemic connective tissue diseases
We tested the applicability of non-commercial antigen substrates obtained from different human and animal tissues, for routine determination of autoantibodies to Sm, (U1)RNP, La and Ro antigens. For the detection of autoantibodies, standard counterimmunoelectrophoresis was used. Reactions of antigens with standard antisera were determined in the following tissue extracts: human liver, kidney, pancreas, spleen and heart obtained at autopsy, and human spleen removed surgically, and animal liver, kidney, spleen and heart (rat, mouse and rabbit). Antigens were extracted in two different media: 0,34 M water solution of sucrose (sah/H2O) and 0,34 M solution of sucrose in phosphate buffer saline (sah/PBS). Reactions with antibodies in standard sera demonstrated the presence of Ro antigen, regardless of the extraction medium, in all human tissue preparations obtained at autopsy (10/10 spleens, 10/10 livers, 10/10 kidneys and 8/8 pancreata), and in all human spleens removed surgically. Also, Ro antigens were detected in all animal tissue extracts. Extraction of La antigen was not medium-dependent, either. It was best demonstrated in extracts of the human liver and kidney (10/10) and in the spleen of rabbit. The occurrence of Sm and (U1)RNP antigens, however, was strongly influenced by the extraction medium used.