Role of anti-nucleosome antibody in the diagnosis of systemic lupus erythematosus.

OBJECTIVE: To investigate the role of anti-nucleosome antibodies (AnuA) in systemic lupus erythematosus (SLE).

METHODS: IgG anti-nucleosome antibodies were detected by enzyme-linked immunosorbent assay (ELISA) in the sera of 233 SLE and 220 other rheumatic diseases' patients as well as 31 health controls. The patients were also evaluated for clinical and biological parameters.

RESULTS: (1) Out of 233 SLE patients, 144 (61.8%) were seropositive for AnuA, which was significantly higher than that of patients with other rheumatic diseases [2.7% (6/220), P < 0.001]; the sensitivities and specificities of AnuA in SLE were 61.8% and 97.6%, respectively. (2) The positive rated of AnuA in SLE lacking of anti-DNP, anti-cmDNA, anti-Sm and anti-dsDNA antibodies were 57.1%, 55.9%, 62.4% and 51.2%, respectively. (3) The frequency of the fever, skin rash, and arthralgia were significantly higher in 144 positive AnuA SLE than those in AnuA negative SLE (P < 0.05). The frequency of leukopenia, elevations of ESR and CRP, lower C3/C4 levels and proteinuria in AnuA positive groups was significantly higher than that of AnuA negative groups (P < 0.05). (4) Level of AnuA was strongly correlated with the SLEDAI scores (r = 0.385, P < 0.001). Patients with active SLE showed significantly higher positive rate of AnuA (66.1%) than those with inactive disease (45.7%) (chi2 = 6.568, P = 0.010).

CONCLUSIONS: AnuA is one of the most valuable markers in the diagnosis of SLE lacking of anti-dsDNA, anti-Sm, anti-DNP and anti-cmDNA antibodies. The level of AnuA is associated with the disease activity of SLE.