ABSTRACT
Introduction. The presence of anti-Ro52 antibodies has been reported in a wide variety of autoimmune diseases, particularly in myositis, scleroderma, and autoimmune liver diseases. Clinical significance of anti-Ro52 antibodies remains controversial, and studies are lacking for clarifying the association of anti-Ro52 with interstitial lung disease (ILD) in connective tissue diseases (CTD). Objectives. To determine if anti-Ro52 antibodies are associated with ILD in CTD other than scleroderma. Methods. Single-center, retrospective study based on immunoblotting panel analysis and patients clinical records. Results. In our connective tissue disease cohort, 162 patients had immunoblotting panels with anti-Ro52 reactivity analysis, 41 (25,3%) had inclusion criteria. Among the 41 selected sera, 85.4% (n = 35) had anti-Ro52 reactivity. The prevalence of ILD in the positive anti-Ro52 antibodies was 71.4% (n = 25), and 16.7% (n = 1) in the negative anti-Ro52 group (P = 0.018). Overall sensitivity (96.2%), specificity (83.3%), positive (71.4%) and negative (83.3%) predictive values of anti-Ro52 antibodies to determine ILD in CTD is detailed in this study. Conclusion. Ro52 autoantibodies are associated with ILD in CTD excluding scleroderma. We suggest that the presence of anti-Ro52 reactivity in CTD should increase the clinician curiosity for the search of ILD.
ABSTRACT
This study evaluates metaphase chromosome protein 1 (MCP1), a nuclear antigen, as a diagnostic marker for systemic lupus erythematosus (SLE). Reactivity of sera from 114 Portuguese patients with autoimmune rheumatic disease or from healthy blood donors (HBD), against MCP1, produced in bacteria (bact-MCP1) or in its native form (native-MCP1), was determined by immunoblotting. Predictive and discriminative power of MCP1 reactivity for SLE diagnosis in disease-control groups was evaluated by logistic regression, its diagnostic value determined by receiver-operating characteristic analysis and compared with similar analysis of antinuclear antibody and double-stranded DNA (dsDNA). We demonstrated that native-MCP1, in contrast to bact-MCP1, reacts with SLE sera with significant predictive and discriminative power versus other autoimmune diseases (odds ratio [OR] ≤3.537 and ≥3.265; area under the receiver-operating characteristic curve [AUC] ≤0.643 and ≥0.636) or versus HBD (OR = 5.006; AUC = 0.671), showing a good diagnostic power with high specificity (82.1% versus HBD) and low sensitivity for SLE, similar to those of dsDNA. The reactivity of SLE sera with native-MCP1 was shown to be dependent on the presence of phosphorylated residues. Native-MCP1 was shown to have diagnostic value as a specific marker for SLE diagnosis and, therefore, is a suitable substrate for a new antibody test. The widely reported importance of phosphorylated epitopes as targets for autoantibodies in SLE could also be confirmed for native-MCP1.
