Anti-nucleosome antibodies as a diagnostic tool in systemic lupus erythematosus and marker of lupus nephritis

Abstract EN

Objective : To evaluate the prevalence of anti-nucleosome antibodies (anti-NCS Abs) in systemic lupus erythematosus (SLE), their role in diagnosis, disease activity and lupus nephritis (LN(.

Methodology : The study was conducted on 23 SLE female patients.

They were divided into two groups according to the presence or absence of LN.

Ten apparently healthy individuals served as a control group.

Clinical assessment was done to all patients especially for renal affection.

Disease activity was scored with SLEDAI.

Anti-NCS and anti-dsDNA antibodies were measured with ELISA.

Renal biopsy was performed for patients with LN.

Results : The prevalence of anti-NCS Abs was (78.3%) and anti-dsDNA Abs was (56.5%) in SLE.

Seventeen patients presented with LN and 6 patients without.

Among these patients, the prevalence of anti-NCS Abs and anti-dsDNA Abs were (88%-64.7%) and (50%-33.3%) respectively.

Anti-NCS Abs were found to be positive in 21.7% of SLE patients lacking anti-dsDNA Abs.

The mean anti-NCS and anti-dsDNA Abs titer in SLE was 250.60+207.00 and 443.3 + 714.3 respectively, showing a highly significant increase compared with healthy controls (12.3 + 4.54 and 31.0 + 20.11) (p < 0.001).

Moreover, in LN and those without LN, the mean anti-NCS Abs showed a highly significant increase (331.41 + 179.73 and 21.67 + 8.36) (p < 0.001), while there was a significant increase in the mean of anti-ds DNA Abs (574.71 + 794.07 and 71.17 + 46.99) (p < 0.05) respectively.

The sensitivity and specificity of anti-NCS Abs in SLE were 82.6% & 100% and in LN were 88.2% & 100% respectively.

Anti-NCS Abs showed a positive significant correlation with ESR (r = 0.900), SLEDAI (r = 0.761) and anti-dsDNA Abs (r = 0.681) in LN, but showed a negative significant correlation with disease duration (r = -0.511) and C4 (r=-0.650) in patients without LN.

In LN 7 patients had proliferative glomerular lesion {WHO class III}, 6 patients class IV and 4 patients class II on renal biopsy.

They were associated with a statistically significant proteinuria, anti-ds DNA and anti-NCS especially in classes II and IV.

Conclusions : Anti-NCS Abs could be a useful parameter for diagnosis and assessment of disease activity and LN in SLE.

It seems to be a more sensitive marker of SLE than anti-ds DNA especially in patients who are anti-dsDNA antibody negative.