CD52 and B-cell chronic lymphocytic leukemia: Although targeting CD20 and CD52 with mAbs can increase progression-free survival and overall survival of CLL patients, immune suppression caused by the expression of these cell surface antigens on normal B cells and other leukocytes can trigger serious infectious complications such as hepatitis B virus reactivation and progressive multifocal leukoencephalopathy following rituximab [7] and cytomegalovirus reactivation and pneumocystis pneumonia following alemtuzumab [8] treatments.