Anti-nucleosome antibodies as a disease marker in systemic lupus erythematosus and its correlation with disease activity and other autoantibodies.
BACKGROUND
Detection of anti-nucleosome antibodies (anti-nuc) in patients with systemic lupus erythematosus (SLE) has been well established and it is claimed that their presence is associated with disease activity.


OBJECTIVE
The aim of this study is to evaluate the incidence of anti-nuc antibodies and to correlate them with disease activity and its association with other autoantibodies like anti-nuclear antibodies (ANA), anti-double stranded DNA (anti-dsDNA), anti-histone antibodies (AHA), as well as autoantibodies to histone subfractions like H1, (H2A-H4) complex, H2B, and H3.


METHODS
This cross-sectional study included 100 SLE patients referred from the Rheumatology, Dermatology, and Nephrology Departments. SLE disease activity was evaluated by using SLE-Disease Activity Index (SLEDAI) score. A patient was defined as having active SLE when the SLEDAI score was more than 5.0. Fifty normal controls were also tested as a healthy control group. Anti-nuc antibodies, anti-dsDNA, and AHA were tested by Enzyme-Linked Immunosorbent Assay (ELISA) and ANA was detected by an indirect immunofluorescence test.


RESULTS
All patients studied were in an active stage of disease and were untreated, of which 44 patients had renal biopsy-proven kidney involvement, which was categorized as lupus nephritis (LN) and 56 patients did not show any renal manifestations (SLE without LN). Anti-nuc antibodies were positive in 88%, anti-dsDNA in 80%, and AHA in 38% of the cases. ANA was positive in all SLE patients studied. None of the normal controls was found to be positive for these antibodies. Although a slightly higher incidence of autoantibodies were noted in LN, there was no statistical difference noted between LN and SLE without LN groups for anti-nuc and anti-dsDNA antibodies (p > 0.05). A higher incidence of autoantibodies to ANA specificities were noted in anti-nuc positive cases, but there was no statistical difference between anti-nuc positive and anti-nuc negative cases for ANA specificities among LN and SLE without nephritis groups (p > 0.05).


CONCLUSIONS
Anti-nuc antibody detection could be a better tool for the diagnosis of SLE. Although there was no significant difference in LN and SLE without LN groups, this study suggests that anti-nuc detection can be useful as an additional disease activity marker to other laboratory tests.
Department of Autoimmune Disorders, National Institute of Immunohematology, Indian Council of Medical Research, 13th floor, KEM Hospital, Parel, Mumbai, India.
Vandana D
VD
Pradhan
Manisha M
MM
Patwardhan
Kanjaksha
K
Ghosh
D000293:Adolescent; D000328:Adult; D000974:Antibodies, Antinuclear / Q000096:biosynthesis / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D003430:Cross-Sectional Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis / Q000276:immunology*; D008297:Male; D009707:Nucleosomes / Q000276:immunology* / Q000378:metabolism; D055815:Young Adult
D000974:Antibodies, Antinuclear; D015415:Biomarkers; D009707:Nucleosomes