Rituximab, a chimeric monoclonal antibody against the B-lymphocyte marker CD 20, has been previously used in open studies in the treatment of patients with systemic lupus erythematosus (SLE), with some success.1 2 Its therapeutic effect is attributed to the profound depletion of native and autoimmune B cells. The initial period of depletion has been reported to last for about 6 months, followed by a repopulation of peripheral B cells 9–12 months after treatment in most cases. We report two cases of prolonged B-cell depletion of 7 and 5 years’ duration, respectively, after a single course of rituximab treatment in two patients with SLE.

A 42-year-old woman with anti-SSA and anti-RNP positive SLE was initially referred to the Centre for Rheumatology Research, University College of London in 1995 for management of persistent fatigue, polyarthritis, Raynaud’s phenomenon and pleurisy. Despite treatment with various immunosuppressive agents, her disease remained clinically and serologically active (table 1). In September 2000 the patient underwent treatment with a single course of rituximab …