Therapeutic B cell depletion and regeneration in rheumatoid arthritis: Emerging patterns and paradigms

In recent controlled clinical trials (1–3), B cell–targeted therapy using rituximab, a chimeric anti-CD20monoclonal antibody, was shown to be effective inpatients with rheumatoid arthritis (RA). However, eventhough use of these anti-CD20 antibody infusions hasbecome increasingly commonplace, especially inhematology/oncology practices, this FDA-approvedtherapeutic modality is still unfamiliar to most rheuma-tologists. Although these treatments predictably inducethe loss of most detectable circulating B lymphocytes,the greater implications of B cell depletion therapy forhost immune defenses are only now slowly being re-vealed.Inthisissueof