Synovial tissue response to treatment with campath‐1h

Objective. Therapeutic trials in rheumatoid arthritis with the monoclonal antibody Campath‐1H have demonstrated recurrent clinical synovitis in some patients, despite profound depletion of circulating lymphocytes. This study was undertaken to examine the cellular infiltrates in synovial tissue at a time of persistent peripheral lymphopenia. Methods. Immunohistochemical staining of synovial tissue and peripheral blood lymphocyte phenotyping. Results. Synovial tissues from 2 patients with recurrent synovitis after Campath‐1H therapy contained significant T lymphocytic infiltrates at a time when circulating T lymphocytes were markedly depleted. Conclusion. These results demonstrate that peripheral blood analysis may not accurately reflect the synovial tissue response to monoclonal antibody therapy.