Rituximab is a human/murine chimeric monoclonal antibody, directed against CD20-positive B cells, that has shown promising activity in the treatment of a broad array of autoimmune diseases including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), idiopathic thrombocytopenic purpura, and IgM-mediated neuropathies [11]. The gene discussed is CD40LG; the disease is rheumatoid arthritis.