AB0385 Anti-chromatin antibodies: a useful marker for early activity.
Authors: A. Arbelaez, C. Mora, C. Romero-Sánchez, P. Valencia-Toro, J. Londono, D. Muñoz, A. Cortes, D. Jaimes, R. Valle-Oñate
Journal: Annals of the Rheumatic Diseases (2013)

<h3>Background</h3> The anti-chromatin antibody is frequently is elevated in patients with active SLE and its titer correlates with activity. <h3>Objectives</h3> The objective of this study is to determine the diagnostic value of anti-chromatin antibodies in the assessment of clinically active SLE. <h3>Methods</h3> A cross-sectional study with 74 patients (110 samples) diagnosed with SLE. Disease activity was evaluated by Safety of Estrogens in SLE National Assessment— SLE Activity Index (SELENA-SLEDAI) and the British Isles Lupus Activity Group 2004 (BILAG 2004) index. Serological titers of anti-dsDNA high avidity, anti-chromatin and anti-C1q antibodies were measured by enzyme-linked immunosorbent assay (ELISA) using commercially available kits INOVA Diagnostics, Inc. Complement levels by nephelometric test Values in this study were expressed as mean ± standard deviation (SD). The chi-squared test was used for the categorical variables as needed. The <i>Wilcoxon Rank-Sum Test</i>was used for comparison of SLEDAI score indices. Correlation among the levels of complements, anti-dsDNA, anti-chromatin, anti-C1q antibodies and disease activity scores was made by the nonparametric Spearman's rank correlation test (correlation coefficient ρ [rho]). Values of p&lt; 0.05 were considered to be of statistical significance. STATA SE-11,1 (STATA Corp®) was used. <h3>Results</h3> The mean SLEDAI score was 3,36 ± 3,19 (0-14). 49,9% (n=54) of patients had a SLEDAI score of ≥ 4. Activity by BILAG A/B: Renal 9% (n=10), mucocutaneous 8,18 (n=9), musculoskeletal 6,5% (n=7), neuropsychiatric 1,8% (n=2), hematological 1,8% (n=2), cardiorespiratory and constitucional 0,9% (n=1). 60% of patients had activity by SLEDAI or BILAG. Biomarkers: Anti-chromatin antibodies 64,08 ± 74,3 (1-251), anti-dsDNA 54,99 ± 77,63 (12-543), anti-C1q antibodies 14,66 ± 23,09 (2-153), C3 97,81± 30,5 (26-152) and C4 16,53 ± 8,99 (2-42). The prevalence of positive anti-chromatin, anti-dsDNA and anti-C1q antibodies in the recruited patients was 51%, 45%, and 16% respectively. Anti-chromatin antibodies and anti dsDNA antibodies were found to be positive in 70% and 72% active-SLE patients by SLEDAI ≥ 4 (p&lt;0,0001). Anti-chromatinantibodies were found to be positive in 15,4% SLE patients lacking anti-dsDNA antibody, 53% without activity for SLEDAI o BILAG at the moment of the study. The <i>Wilcoxon Rank-Sum Test</i>showed an excellent correlation between anti-chromatin antibodies and SLEDAI score ≥ 4 (p&lt; 0,0001). Spearman's rank correlation test (<b>ρ)</b> among the levels of anti-chromatina and anti-dsDNA with disease activity scores was 0,38 (p&lt;0,001) and 0,41 (p&lt;0,001) respectively. <h3>Conclusions</h3> Anti-chromatincould precede the development of lupus flares and thus has a value in predicting lupus flares and preempting treatment. <h3>References</h3> Translational Research 2012;159:326–342. Arthritis Research &amp; Therapy 2009, 11:R154. Ann Rheum Dis 2007;66:693–696. <h3>Disclosure of Interest</h3> None Declared