EXPRESSION OF THE CUTANEOUS LYMPHOCYTE ANTIGEN AND ITS COUNTER-RECEPTOR E-SELECTIN IN THE SKIN AND JOINTS OF PATIENTS WITH PSORIATIC-ARTHRITIS

We have investigated whether the skin-homing T lymphocytes identified by the cutaneous lymphocyte antigen (CLA) are increased in the synovia l membrane of patients with psoriatic arthritis. Twenty-six synovial s amples (13 psoriatic arthritis, seven rheumatoid arthritis, six osteoa rthritis) were obtained from involved knees. Lesional skin biopsies we re taken from nine of the patients with psoriatic arthritis and six pa tients with psoriasis alone. All samples were single- and dual-stained for CLA and CD3 (to identify T lymphocytes) using HECA-452 (anti-CLA) and anti-CD3 monoclonal antibodies. E-selectin expression was also de termined. The percentage of dual-stained lymphocytes was significantly greater in psoriatic skin than in synovium (P < 0.001) and similar be tween psoriatic and rheumatoid synovium. There was no significant diff erence in the percentages of CLA-positive cells in psoriatic skin in p atients with psoriatic arthritis compared with psoriasis alone. The in tensity of endothelial E-selectin expression was significantly greater in skin psoriasis than in synovium (P < 2 x 10(-5)), and rheumatoid s ynovium had significantly greater expression than psoriatic synovium ( P < 0.05). However, there was no significant correlation between E-sel ectin expression and the percentages of CLA-positive lymphocytes. This study provides further evidence that the CLA antigen is enriched on s kin-homing lymphocytes. Conversely, the link between skin and joint in flammation in psoriatic arthritis does not seem to be explained by inc reased trafficking of CLA T cells to psoriatic synovium.