Autoantigen-specific memory B cells in primary Sjögren's syndrome

Area of Science:

• Immunology
• Rheumatology
• Autoimmune Diseases

Background:

• Sjögren's syndrome (SS) is a systemic rheumatic autoimmune disease impacting exocrine glands.
• It is characterized by autoantibodies against SS-A/Ro and SS-B/La ribonucleoprotein particles and mononuclear cell infiltration.
• Understanding memory B cell dynamics is crucial for characterizing disease progression in primary SS.

Purpose of the Study:

• To characterize the pattern and function of memory B cells in primary Sjögren's syndrome.
• To investigate the relationship between memory B cell activity and disease progression.
• To quantify autoantibody-specific plasma cells and memory B cells in SS patients.

Main Methods:

• Analysis of peripheral blood mononuclear cells (PBMC) from 23 primary SS patients and 20 healthy controls.
• Direct enzyme-linked immunospot (ELISPOT) assay to measure Ro/La-specific plasma cells.
• In vitro polyclonal stimulation of PBMC followed by antigen-specific ELISPOT to quantify memory B cells.
• ELISA profiling of autoantibodies in patient plasma and PBMC supernatant.

Main Results:

• Elevated levels of Ro60-, Ro52-, and La48-specific plasma cells were observed in SS patients' PBMC.
• In vitro stimulation significantly increased the number of antibody-secreting cells, indicating a pool of responsive B cells.
• The fraction of activated memory B cells secreting antibodies was lower than the total IgG B cell population, suggesting a higher activation state.

Conclusions:

• Lower Ro/La-specific memory B cell levels in SS patients may indicate a greater proportion of these cells are already activated.
• This heightened activation state of B cells likely contributes to the autoimmune pathology in Sjögren's syndrome.
• Findings support the role of specific B cell subsets in the ongoing autoimmune response in primary SS.