T cell receptor expression in Sjögren's syndrome

Area of Science:

• Immunology
• Rheumatology
• Cell Biology

Background:

• Expanded populations of T lymphocytes (gamma/delta T cell receptor) and B lymphocytes (CD5) are observed in primary Sjögren's syndrome peripheral blood.
• Understanding the cellular infiltrates in Sjögren's syndrome is crucial for elucidating disease mechanisms.

Purpose of the Study:

• To investigate the surface phenotypic markers of cellular infiltrates in lip biopsies from patients with primary and secondary Sjögren's syndrome.
• To determine the role of alpha/beta and gamma/delta T cell receptor-bearing lymphocytes in Sjögren's syndrome immunopathology.

Main Methods:

• Analysis of cellular infiltrates in lip biopsy specimens using surface phenotypic markers.
• Flow cytometry was used to identify T lymphocytes (alpha/beta and gamma/delta T cell receptors, CD4, CD8) and B lymphocytes (CD5, CD45).

Main Results:

• The majority of cellular infiltrates in Sjögren's lip biopsies were CD4+ T lymphocytes expressing the alpha/beta T cell receptor (mean 70%).
• A low prevalence of gamma/delta T cell receptor-bearing cells (mean 1.5%) was observed in lip biopsies, suggesting a limited role in pathogenesis.
• Over 70% of cells in lesional infiltrates expressed CD5 and CD45 cell surface molecules in both primary and secondary Sjögren's syndrome.

Conclusions:

• The immunopathology of Sjögren's syndrome primarily involves CD4+ alpha/beta T lymphocytes, not gamma/delta T cell receptor-bearing lymphocytes.
• CD5 and CD45 expression is characteristic of the lesional infiltrate in Sjögren's syndrome, indicating a B cell or activated T cell component.