Determination of Autoantibodies by Line Immunoblotting

[Methods of autoantibody diagnostics - when immunofluorescence test, when ELISA?]

The detection of circulating autoantibodies against a variety of structural and functional molecules present in ubiquitous or tissue-specific cells is critical to the diagnosis of many autoimmune diseases (systemic - such as systemic rheumatic diseases - and organ-specific diseases). In particular, the determination of autoantibodies is one of the classification and/or diagnostic criteria for some autoimmune diseases and has a relevant predictive value, since many autoantibodies can be detected years before the clinical manifestation of a disease.The identification of these antigen-antibody systems and the simultaneous development of laboratory methods for detecting and measuring autoantibodies are considered one of the milestones in the history of clinical immunology over the last 60 years. Many different immunoassay methods have been developed and used in laboratory practice, from the early conventional (or monoplex) analytical methods that can detect single autoantibodies to the newer multiplex platforms that can quantify dozens of molecules. Various diagnostic immunoassays commonly used in current laboratory practice for the detection of autoantibodies are presented in this review.

Clinical significance of anti-Ro52 (TRIM21) antibodies in adult patients with connective tissue diseases

OBJECTIVES

Clinical significance of anti-Ro52 antibodies in connective tissue diseases (CTD) is controversial. Anti-Ro52 antibodies might be associated with a more severe CTD phenotype, especially interstitial lung disease (ILD). The aims of this study were to evaluate ILD prevalence and severity, the prevalence of micro- or macroangiopathy and CTD-associated cancers in CTD with anti-Ro52 antibodies.

METHODS

CTD patients with anti-Ro52 antibody screening by immunoblot at diagnosis were enrolled. Two groups were retrospectively formed according to the presence of anti-Ro52 antibodies with an unbiased 1:1 matching on CTD types. Unsupervised multiple correspondence analysis and hierarchical clustering analysis were used to aggregate anti-Ro52 positive patients in subgroups.

RESULTS

408 CTD patients were included. Anti-Ro52 antibodies were detected in 33 % of CTD patients. Anti-Ro52 antibodies were associated with ILD at CTD diagnosis (47.8% vs. 23.0%, OR 3.3 95% IC 1.4 to 8.0, p = 0.008), even after adjusting for the presence of anti-Ro60 antibodies, especially in patients with antisynthetase syndrome, primary Sjögren syndrome and systemic sclerosis. Micro- or macroangiopathy was more frequent in anti-Ro52 positive CTD patients (18.6% vs. 9.7%, p = 0.02) and CTD patients with anti-Ro52 antibodies experienced more frequent relapses and required more immunosuppressive drugs. Clusters 4 and 5 identified anti-Ro52 positive CTD patients with severe ILD and with clinical features of systemic sclerosis or antisynthetase syndrome respectively.

CONCLUSIONS

We found that anti-Ro52 antibodies were independently associated with ILD in CTD patients irrespective of CTD type. Anti-Ro52 antibodies could be associated with severity and a more relapsing disease course in CTD patients.