Contains the following antigenic components from human whole cell extract as tested by western blot: SS-A (Ro) with 60 kD and 52 kD bands, SS-B (La) with 50 kD band (note that the SS-A 52 kD and the SS-B 50 kD bands overlap due to their size), Scl-70 (topoisomerase I) with 105 kD band, RNP with 68 kD and 33 kD bands, Smith with 26 kD and 25 kD bands, Jo-1 with 53 kD band, and Ribosomal P with 38 kD band.