Cell-free CD5 in patients with rheumatic diseases

Area of Science:

• Immunology
• Biochemistry

Background:

• Increased CD5+ B cells are observed in rheumatoid arthritis (RA) and primary Sjögren's syndrome (SS).
• Reduced CD5 expression on T cells is noted in some SS patients.
• These observations suggest a potential alteration in CD5 turnover in these autoimmune disorders.

Purpose of the Study:

• To investigate the hypothesis of accelerated CD5 turnover in RA and SS.
• To develop and validate a novel enzyme-linked immunosorbent assay (ELISA) for quantifying cell-free CD5 (CF-CD5).

Main Methods:

• Development of a novel ELISA using specific anti-CD5 antibodies for capture and detection.
• Measurement of CF-CD5 levels in sera from patients with RA, SS, ankylosing spondylitis, and healthy controls.

Main Results:

• CF-CD5 was detectable in sera from RA and SS patients, but not in those with ankylosing spondylitis or normal controls.
• CF-CD5 levels did not correlate with rheumatoid factor in RA patients.
• SS patients with extraglandular manifestations showed significantly higher CF-CD5 levels compared to those with glandular disease.
• A subset of SS patients with glandular disease and increased CD5-negative T cells did not exhibit elevated CF-CD5 levels.

Conclusions:

• The novel ELISA effectively detects CF-CD5 in human sera.
• Elevated CF-CD5 levels are associated with RA and SS, indicating altered CD5 turnover.
• Higher CF-CD5 levels in SS correlate with extraglandular disease, suggesting its potential as a biomarker.