Different rheumatoid factor binding patterns distinguish between Sjögren's disease with or without associated RA.

Area of Science:

• Rheumatology and Immunology
• Autoimmune Diseases Research

Background:

• Rheumatoid arthritis (RA) and Sjögren's disease (SjD) are autoimmune rheumatic diseases that frequently co-occur.
• Both conditions often present with rheumatoid factors (RFs), which are autoantibodies targeting the IgG-Fc region.
• Previous research indicated distinct RF reactivity profiles in RA versus SjD patients.

Purpose of the Study:

• To investigate whether RF binding patterns in patients with co-occurring RA and SjD (SjD-RA) resemble RA, SjD, or a combination.
• To determine if RF profiles can aid in differentiating between SjD, SjD-RA, and RA.

Main Methods:

• Quantified IgM- and IgA-RF levels against specific IgG-Fc epitopes.
• Assessed RF binding patterns in 14 SjD-RA patients.
• Compared SjD-RA patterns with those from 28 early RA patients and 152 SjD patients.

Main Results:

• SjD-RA patients exhibited IgM-RF and IgA-RF profiles similar to RA patients, differing significantly from SjD patients.
• RF presence and binding patterns in SjD patients were linked to anti-SSA/Ro antibodies.
• Distinct RF reactivity profiles were observed across SjD-RA, RA, and SjD cohorts.

Conclusions:

• RF binding pattern analysis is a valuable tool for distinguishing between SjD, SjD-RA, and RA.
• This approach enhances understanding of the complex immunological interplay in co-occurring autoimmune conditions.