Antinucleosome antibodies in systemic lupus erythematosus patients: Relation to disease activity and lupus nephritis

Aim of the work: To evaluate the level of anti-nucleosome (anti-NCS) antibodies in systemic lupus erythematosus (SLE) patients and study their association with disease activity and lupus nephritis. Patients and methods: The study was carried out on 50 SLE patients; 47 females and 3 males and 30 matched controls. The SLE disease activity index (SLEDAI) was assessed. Plasma levels of anti-NCS antibodies were measured. Renal biopsy was done in those with lupus nephritis. Results: The mean age of patients was 28.3 ± 12.9 years; disease duration was 5.5 ± 6.02 years and the SLEDAI.5 ± 7.8. LN was present in 60% of the patients. Anti-nuclear antibodies (ANA) were positive in 48 (96%) and the anti-double stranded deoxyribonucleic acid positive in 38 (76% of the patients. The anti-NCS antibodies level was significantly increased in the patients (470.1 ± 369.4 U/ml) compared to the control (36.43 ± 14.58 U/ml) (p = 0.0001). The anti-NCS was detected in 48/50(96%) patients at a cut-off of 65 U/ml. There was no significant difference in the anti-NCS antibodies levels between those with nephritis (456.53 ± 362.59 U/ml) and those without (490.4 ± 387.96 U/ml) (p = 0.84). A significant correlation was present between the anti-NCS antibodies and photosensitivity (p = 0.032), ESR (p = 0.03), complement (C3) consumption (p = 0.01) and urinary casts (p = 0.04). A non-significant correlation was detected between level of anti-NCS and grades of nephritis (p = 0.49) or SLEDAI (p = 0.09). Conclusion: Anti-NSC antibodies could be a useful addition to the laboratory tests that can help in the diagnosis of SLE. Also, it has a significant association to photosensitivity but no relation to with disease activity or renal involvement. Keywords: Systemic lupus erythematosus, Lupus nephritis, Antinucleosome antibodies, Disease activity, Anti-dsDN