Extractable nuclear antigens (ENAs) are detected in the sera of the majority of patients with rheumatic systemic disease. The main ENAs studied are SS-A/Ro, SS-B/La, RNP, Sm, Scl-70 and Jo-1. The aim of this work was: a) to standardize the counterimmunoelectrophoresis technique (CIE) to detect ENAs; b) to standardize the extration of ENAs from dog spleen as a substract for CIE test; c) to compare the results obtained by CIE with those of indirect immunofluorescence (IFI) and Elisa for these antigens. Forty sera from individuals with rheumatic systemic disease confirmed by clinical and serological tests and by skin and/or kidney biopsies were tested. Ten normal sera from blood donors were used as negative control, and as positive control to check for ENAs in the spleen extract, six positive sera for anti-Ro, anti-La, anti-RNP, anti-Sm, anti-Scl-70, anti-Jo-1 were tested. The spleen extract contained many of the ENAs antigens, except RNP and Scl-70. CIE showed good sensitivy (70%) and specificity (100%) in relation to IFI and Elisa. Also, by CIE the positive sera could be diluted up to 16 dilution (32.5%). We concluded that CIE, together with antigens extracted from dog spleen, could be used in the laboratorial routine to detect ENAs, and compared to IFI, with the advantage that sera can be titulated.
Autoantibodies; Serologic tests; Extractable nuclear antigens; Counterimmunoelectrohoresis
