PT  - JOURNAL ARTICLE
AU  - SJÖWALL, CHRISTOPHER
AU  - STURM, MARTIN
AU  - DAHLE, CHARLOTTE
AU  - BENGTSSON, ANDERS A.
AU  - JÖNSEN, ANDREAS
AU  - STURFELT, GUNNAR
AU  - SKOGH, THOMAS
TI  - Abnormal Antinuclear Antibody Titers Are Less Common Than Generally Assumed in Established Cases of Systemic Lupus Erythematosus
DP  - 2008 Oct 01
TA  - The Journal of Rheumatology
PG  - 1994--2000
VI  - 35
IP  - 10
4099  - http://www.jrheum.org/content/35/10/1994.short
4100  - http://www.jrheum.org/content/35/10/1994.full
SO  - J Rheumatol2008 Oct 01; 35
AB  - Objective To evaluate antinuclear antibody (ANA) tests in established cases of systemic lupus ery-thematosus (SLE) and rheumatoid arthritis (RA) by indirect immunofluorescence microscopy (F-ANA) and enzyme-immunoassays detecting antinucleosomal antibodies (ANSA-EIA). Methods Sera from 50 patients with SLE and 65 patients with RA were analyzed regarding abnormal concentrations of F-ANA (serum dilution ≥ 1:200 = 95th percentile among 300 healthy blood donors). The sera were also analyzed with 2 commercial ANSA-EIA kits. Results An abnormal F-ANA titer occurred in 76% of the SLE sera compared to 23% in RA, and was not related to present use of antirheumatic drugs. At dilution 1:50, 84% of the SLE sera were F-ANA-positive compared to 20% of healthy women. Forty percent and 56%, respectively, of the SLE sera tested positive in the 2 ANSA-EIA kits. By the most sensitive assay, 96% of the ANSA-positive SLE sera produced a homogenous (chromosomal) F-ANA staining pattern compared to 18% of the ANSA-negative SLE sera. Ten of the 15 F-ANA-positive RA sera (63%) generated homogenous F-ANA staining and 13 (20%) tested positive in the most sensitive ANSA-EIA, but with no correlation to the F-ANA staining pattern. Conclusion The sensitivity of F-ANA at an abnormal titer was surprisingly low (76%) in established cases of SLE. ANSA occurred in 56% of the SLE sera, but also in a fair number (20%) of RA sera. Practically all ANSA-positive SLE sera were identified by chromosomal F-ANA staining. We conclude that the antigen-specific antinucleosomal EIA does not have high enough diagnostic specificity to justify use of this analysis for routine diagnostic purposes.