Decreased CD20 expression in rheumatoid arthritis synovium following 8 weeks of rituximab therapy

To characterise the effects of rituximab on synovial tissue of patients with refractory rheumatoid arthritis (RA). Arthroscopic biopsy of knee joint synovium was performed on 6 patients with seropositive RA prior to commencing rituximab. Four patients underwent repeat biopsy eight weeks following completion of their rituximab infusion schedule. Cryostat sections of synovium were prepared and stained with mouse monoclonal specific antibodies including CD20, plasma cell antibody and CD68. Eight weeks after treatment mean DAS28 fell from 6.6+/-0.43 to 4.7+/-0.49 (p=0.068). Mean CRP fell from 86.7+/-27 mg/L to 20.5+/-7 mg/L (p