CD6 and rheumatoid arthritis: Consistent with these findings, a humanized anti-CD6 monoclonal antibody, itolizumab, has been shown to be effective for the treatment of psoriasis and rheumatoid arthritis (56,57), owing to its ability to inhibit T-cell activation, proliferation, and production of proinflammatory cytokines (58,59), and is being studied as a therapy for acute graft-vs-host disease (60).