CD52 and rheumatoid arthritis: Some patients with rheumatoid arthritis (RA) remain lymphopenic 12 years after alemtuzumab (anti-CD52) treatment, and the analysis of their peripheral T cell compartments shows that naïve and central memory T cell (TCM) numbers are reduced, while that of effector memory T cells (TEM) is similar to that of RA patients not treated with alemtuzumab (32).