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 bythe cutaneous lymphocyte antigen (CLA) are increased in the synovialmembrane of patients with psoriatic arthritis. Twenty-six synovial samples(13 psoriatic arthritis, seven rheumatoid arthritis, six osteoarthritis)were obtained from involved knees. Lesional skin biopsies were taken fromnine of the patients with psoriatic arthritis and six patients withpsoriasis alone. All samples were single- and dual-stained for CLA and CD3(to identify T lymphocytes) using HECA-452 (anti-CLA) and anti-CD3monoclonal antibodies. E-selectin expression was also determined. Thepercentage of dual-stained lymphocytes was significantly greater inpsoriatic skin than in synovium (P < 0.001) and similar betweenpsoriatic and rheumatoid synovium. There was no significant difference inthe percentages of CLA-positive cells in psoriatic skin in patients withpsoriatic arthritis compared with psoriasis alone. The intensity ofendothelial E-selectin expression was significantly greater in skinpsoriasis than in synovium (P < 2 x 10(- 5)), and rheumatoid synoviumhad significantly greater expression than psoriatic synovium (P < 0.05).However, there was no significant correlation between E-selectin expressionand the percentages of CLA- positive lymphocytes. This study providesfurther evidence that the CLA antigen is enriched on skin-hominglymphocytes. Conversely, the link between skin and joint inflammation inpsoriatic arthritis does not seem to be explained by increased traffickingof CLA T cells to psoriatic synovium.