Positive rates of six antibodies in systemic lupus erythematosus:a comparative analysis in 47 cases

Objective To estimate the sensitivity of six antibodies in diagnosing systemic lupus erythematosus (SLE). Methods SLE patients in Division of Rheumatology and health checkup subjects from our hospital between October 2008 and December 2010 were selected and studied for ANUA and AHA with enzyme-linked immunosorbent assay (ELISA), ANA and anti-dsDNA antibody with immunofluorescence, Anti-SSA and anti-SSA antibodies with enzyme linked immunoblot assay. The results of anti-SSA and anti-SSA antibodies were confirmed by double immunodiffusion. Results The positive rate was 77% for ANUA, 43% for AHA, 32% for anti-dsDNA antibody, 28% for anti-Sm antibody, 94% for ANA, and 17% for anti-SSA antibody. Conclusion Positive rate of ANUA (77%) was evidently higher than that of anti-dsDNA antibody (32%) and anti-Sm antibody (28%) (P0.05), and therefore ANUA may be a more specific indicator than anti-dsDNA antibody in diagnosing SLE, especially useful for anti-dsDNA-negative patients. Anti-dsDNA and anti-Sm antibodies are highly specific in diagnosing SLE, but low sensitivity of them leads to low positive rates. Although with a high positive rate, AHA shows low specificity and hence is suitable only for SLE screening test. The lowest positive rate of anti-SSA (17%) among the six antibodies dismisses its use for screening, but its true negative rate appears high. Combined detection of 6 antibodies may minimize the limitations of single ones, and may be useful in diagnosis and treatment of SLE.