Latest update on the Ro/SS-A autoantibody system

Area of Science:

• Immunology
• Autoimmunity
• Serology

Background:

• Anti-SS-A (Ro52/Ro60) autoantibodies are associated with Sjögren's syndrome and other autoimmune diseases.
• Historically, anti-SS-A autoantibodies were viewed as a single entity.
• Recent evidence suggests Ro60 and Ro52 are not a stable complex, with differing clinical associations.

Purpose of the Study:

• To investigate the distinct clinical associations of anti-Ro52 and anti-Ro60 (SS-A) autoantibodies.
• To highlight the limitations of using a combined antigen assay for SS-A detection.
• To emphasize the need for separate detection of anti-Ro52 and anti-Ro60 (SS-A).

Main Methods:

• Analysis of clinical associations of anti-Ro52 and anti-Ro60 (SS-A) antibodies.
• Evaluation of recombinant Ro60 (SS-A) ELISA performance.
• Characterization of international reference sera (CDC).

Main Results:

• Anti-Ro52 prevalence is higher in systemic sclerosis and myositis compared to anti-Ro60 (SS-A).
• Isolated anti-Ro52 antibodies are found in up to 37% of myositis patients, often with anti-Jo-1 reactivity.
• Combined antigen assays may miss up to 20% of single anti-Ro52 or anti-Ro60 (SS-A) reactivity.

Conclusions:

• Ro60 (SS-A) and Ro52 represent two distinct autoantibody systems.
• Separate detection of anti-Ro52 and anti-Ro60 (SS-A) is crucial for accurate clinical diagnosis.
• Current combined SS-A assays may lead to underdiagnosis of specific autoantibody reactivities.