Certain rheumatoid factors react with both IgG and an antigen associated with cell nuclei

Area of Science:

• Immunology
• Rheumatology
• Cell Biology

Background:

• Rheumatoid factors (RF) are autoantibodies primarily targeting human IgG.
• Anti-nuclear antibodies (ANA) are associated with autoimmune diseases and target nuclear components.

Purpose of the Study:

• To investigate the potential cross-reactivity of rheumatoid factors with nuclear antigens.
• To characterize antibodies exhibiting dual reactivity with IgG and nuclear components.

Main Methods:

• Isolation of RF based on affinity for human IgG.
• Screening of RF-positive sera for anti-nuclear antibody activity.
• Characterization of RF/ANA activity using IgG-agarose conjugates and Fcgamma fragments.

Main Results:

• 12% of sera with high RF and ANA titers showed cross-reactivity with mouse cell nuclei, termed RF/ANA.
• One serum (Nil) contained significant RF/ANA, while another (Jos) had high RF and ANA levels.
• Purified RF/ANA demonstrated inhibition by aggregated human IgG, Fcgamma fragments, and mouse anti-DNP antibodies.

Conclusions:

• Certain autoantibodies possess dual specificity, binding to both IgG and nuclear antigens.
• This RF/ANA subset represents an uncharacterized proportion of RF with potential implications in autoimmunity.