Dendritic cells in rheumatoid synovial membrane after total removal of the hyaline articular cartilage

Objective. To investigate the effect of total removal of the hyaline articular cartilage on dendritic cells in synovial membrane in rheumatoid arthritis (RA) or ankylosing spondylitis (AS). Patients and methods. Immunohistochemical staining for two dendritic cell markers, CD35 and RFD1, was carried out on synovial membrane specimens from arthritis patients undergoing primary (n = 10) or revision (n = 8) total hip replacement (THR). The results are expressed as the number (mean standard deviation) of positive cells per 1000 total cells. Results. CD35-(112 +/- 9) and RFD1-(27 +/- 5) positive cells were found in all primary RA synovial membrane, while only two out of eight synovial membrane samples from revision THR contained CD35-positive follicular dendritic cells (nine and 12 cells). and no revision samples contained any RFD1-positive interdigitating dendritic cells. Conclusion. Removal of the hyaline articular cartilage reduces the infiltration and functional differentiation of dendritic cells in synovial membrane. Our findings suggest that the antigen driving chronic arthritis/synovitis is contained in the hyaline articular cartilage.