The CD52 (HI186) antibody recognizes a 25-29 kDa glycosylphosphatidylinositol (GPI)-anchored single chain glycoprotein typically e, Xenopus/Amphibian,pressed at high levels on thymocytes, lymphocytes, NK cells,Mouse,onocytes/macrophages. CD52 is e, Xenopus/Amphibian,pressed at 2% on some granulocytes and epithelial cells of male reproductive tract, and also e, Xenopus/Amphibian,pressed at variable levels on the majority of lymphoid malignancies, but not on erythrocytes and platelets. A somatic defect in the synthesis of GPI anchors causes a lack of CD52 antigen on cell surface on lymphocytes from patients with paro, Xenopus/Amphibian,ysmal nocturnal haemoglobinuria (PNH) . CD52 may be used to diagnose PNH besides CD55 and CD59. All CD52 antibodies are characterized by a strong lytic activity with human complement, irrespective of antibody isotype.