Correlation of antiperinuclear factor with antibodies to streptococcal cell-wall peptidoglycan-polysaccharide...

Area of Science:

• Immunology
• Rheumatology
• Microbiology

Background:

• Antiperinuclear factor (APF) is prevalent in rheumatoid arthritis (RA) and juvenile rheumatoid arthritis (JRA).
• The precise nature of the APF antigen remains elusive, with hypotheses suggesting glycoprotein or proteoglycan composition.

Purpose of the Study:

• To investigate the correlation between APF and antiproteoglycan antibodies.
• To examine the reactivity of IgM-rheumatoid factor (RF) with the perinuclear antigen.
• To explore potential antigenic similarities between the perinuclear antigen and Streptococcal cell wall components.

Main Methods:

• Serum samples from JRA patients were fractionated into IgG, IgM, and IgM-RF enriched components.
• APF activity was assessed in these fractions.
• Antibodies to Streptococcal cell wall peptidoglycan-polysaccharide polymers (PG-PSP) were measured.
• APF activity was tested after adsorption with Streptococcal cell wall PG-PSP.

Main Results:

• APF was detected in both IgG and IgM fractions of JRA sera, indicating polyclonal antibody nature.
• A significant correlation was observed between APF positivity and the presence of anti-PG-PSP antibodies.
• Adsorption with Streptococcal cell wall PG-PSP reduced APF activity in 75% of APF-positive sera.
• While APF correlates with RF positivity, not all IgM-RF fractions exhibited APF activity.

Conclusions:

• APF in JRA comprises polyclonal IgG and IgM antibodies.
• The findings strongly suggest cross-reactivity between APF and antibodies to Streptococcal cell wall PG-PSP.
• This cross-reactivity implies an antigenic similarity between the perinuclear antigen and Streptococcal cell wall PG-PSP, offering insights into RA pathogenesis.