Aim To evaluate the sensitivity of a commercial autoantibody screening method (Phadia EliA connective tissue disease (CTD) screen) for the detection of less common antibody specificities associated with connective tissue disease.

Methods 399 sera positive for anti-PM/Scl (n=102), anti-RNA polymerase III (n=199), anti-fibrillarin (n=50), anti-Mi-2 (n=12), anti-proliferating cell nuclear antigen (PCNA) (n=13) and anti-ribosomal P (n=23) were analysed using the solid phase assay. Each well was coated with the respective antigens for these autoantibodies and also with the antigens Ro, La, Jo-1, Scl-70, CENP-B, U1-RNP, Sm and native DNA.

Results All the anti-ribosomal P, anti-PCNA and anti-Mi-2 sera and 94% of the anti-PM/Scl sera were positive. For anti-fibrillarin, 36 (68%) were positive and 12 (22%) were equivocal. For anti-RNA polymerase III, 131 (67%) were positive, 23 (11%) were equivocal and 45 (22%) were negative.

Conclusions The sensitivity of the Phadia EliA CTD screen is currently insufficient for the assay to be used as a screening test for anti-fibrillarin and anti-RNA polymerase III, but appears to be satisfactory for the other autoantibodies tested.