Peripheral B-Cell Subset Distribution in Primary Antiphospholipid Syndrome

Area of Science:

• Immunology
• Autoimmune Diseases
• Cell Biology

Background:

• B-cell differentiation and tolerance checkpoints may differ between antiphospholipid syndrome (APS) and systemic lupus erythematosus (SLE).
• Understanding these differences can elucidate distinct disease mechanisms.
• This study aimed to define B-cell subset alterations in primary APS (pAPS) and compare them to SLE and healthy controls (HC).

Purpose of the Study:

• To characterize peripheral blood B-cell phenotypes in patients with primary antiphospholipid syndrome (pAPS).
• To compare B-cell subset frequencies in pAPS with those in systemic lupus erythematosus (SLE) and healthy controls (HC).
• To investigate serum levels of B cell-activating factor (BAFF) and IL-6 in these groups.

Main Methods:

• A cross-sectional study involving 37 pAPS patients, 11 SLE patients, and 21 HC.
• Quantification of B-cell subset frequencies in peripheral blood (naïve and memory compartments).
• Measurement of serum BAFF and IL-6 levels using ELISA and CBA.

Main Results:

• pAPS patients exhibited lower immature and naïve B cells but higher non-switched memory B cells compared to SLE patients.
• Serum BAFF levels were elevated in SLE patients versus HC and pAPS patients, and also increased in pAPS versus HC.
• Both SLE and pAPS patients showed higher circulating IL-6 levels than HC, with a positive correlation between BAFF and IL-6 in SLE but not pAPS.

Conclusions:

• Peripheral blood B-cell phenotypes in pAPS reveal distinct differentiation stage frequencies.
• Differences in the naïve B-cell repertoire may account for the greater autoantibody diversity observed in SLE compared to pAPS.
• These findings highlight unique B-cell dynamics in pAPS relevant to autoimmune disease pathogenesis.