Autoimmune sera react with multiple epitopes on recombinant 52 and 60 kDa Ro(SSA) proteins

Area of Science:

• Immunology
• Autoimmunity
• Molecular Biology

Background:

• Ro autoantibodies are associated with autoimmune diseases like neonatal lupus erythematosus (NLE), subacute cutaneous lupus erythematosus (SCLE), and Sjögren's syndrome (SS).
• Accurate detection of Ro autoantibodies is crucial for diagnosis and understanding disease pathogenesis.

Purpose of the Study:

• To evaluate the reactivity of recombinant 52 and 60 kDa Ro (SSA) proteins with sera from patients diagnosed with NLE, SCLE, and SS.
• To investigate the presence of multiple epitopes on Ro autoantigens.

Main Methods:

• Recombinant glutathione S-transferase (GST) fusion proteins of 52 and 60 kDa Ro autoantigens were expressed.
• Patient sera (NLE, SCLE, SS) were tested using enzyme-linked immunosorbent assay (ELISA) against recombinant Ro fusion proteins.
• Ro autoantibody reactivity was compared between ELISA and double immunodiffusion (ID) assays.

Main Results:

• High reactivity rates were observed for both 52 kDa (75% NLE, 56% SCLE, 83% SS) and 60 kDa (75% NLE, 63% SCLE, 83% SS) Ro fusion proteins with patient sera.
• A significant proportion of Ro autoantibody-negative sera (57%) showed reactivity by ELISA, indicating potential cross-reactivity or novel epitope detection.
• ELISA studies with Ro protein fragments identified at least two major epitopes on both 52 and 60 kDa Ro proteins, with a leucine zipper motif-containing fragment reacting with 100% of SS sera.

Conclusions:

• The combination of ID and recombinant Ro ELISA offers enhanced sensitivity for Ro autoantibody detection compared to individual assays.
• The study confirms the presence of multiple immunogenic epitopes on both 52 and 60 kDa Ro (SSA) proteins.
• These findings contribute to a better understanding of Ro autoantibody-associated diseases and diagnostic strategies.