Alemtuzumab (Lemtrada®; Campath®; Genzyme), is a humanized anti-CD52 mAb used to avoid immune rejection by bone-marrow [23, 60] and renal [182] transplantation or treat chronic lymphocytic leukaemia (CLL) [91] and multiple sclerosis [67] by depleting CD52-expressing cells, such as CD4+ and CD8+ T cells, monocytes and nature killer cells (NK cells). This evidence concerns the gene CD4 and B-cell chronic lymphocytic leukemia.