Anti-Ro/SSA and La/SSB antibodies.
The Ro/La system is considered as an heterogeneous antigenic complex, constituted by three different proteins (52 kDa Ro, 60 kDa Ro and La) and four small RNAs particles. Anti-Ro/SSA are the most prevalent specificity among many autoimmune diseases, such as systemic lupus erythematosus (SLE), SS/SLE overlap syndrome, subacute cutaneous LE (SCLE), neonatal lupus and primary biliary cirrhosis. In contrast, anti-La/SSB is more associated with Sjögren's syndrome (SS). The differences between 52 kDa, 60 kDa Ro and La could explain why different assays did not show equivalent performance in anti-Ro and anti-La autoantibodies detection. The RNA precipitation assay had the highest sensitivity and specificity, usually considered as the reference methods. CIE is considered the most reliable to detect anti-Ro/SSA antibodies in routine practice, performing better than immunoblotting (IB) and some ELISAs. It shows a high sensitivity (89%) and specificity (100%). ELISA is generally considered a safe, rapid, sensitive and specific tecnique. Therefore, its high sensitivity often corresponds to a very low clinical specificity and the assay can give false positive results. Therefore, it is very important to search anti-Ro and anti-La only in selected patients, using the assay with high specificity and good predictive value, in order to have clinically significant and true positive results.
Franceschini
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F
Servizio di Reumatologia, Allergologia, Immunologia Clinica Spedali Civili di Brescia, Italy.
Cavazzana
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I
D000465:Algorithms; D000974:Antibodies, Antinuclear / Q000097:blood* / Q000266:history; D049673:History, 20th Century; D006801:Humans; D007118:Immunoassay / Q000379:methods / Q000706:statistics & numerical data; D007132:Immunoglobulin Isotypes / Q000097:blood; D008180:Lupus Erythematosus, Systemic / Q000276:immunology; D012680:Sensitivity and Specificity; D012859:Sjogren's Syndrome / Q000276:immunology
D000974:Antibodies, Antinuclear; D007132:Immunoglobulin Isotypes; C035356:SS-A antibodies; C035357:SS-B antibodies