title: Crry, but not CD59 and DAF, is indispensable for murine erythrocyte protection in vivo from spontaneous complement attack.
abstract: Decay-accelerating factor (DAF) and CD59 are 2 glycosylphosphatidylinositol-anchored membrane proteins that inhibit complement activation at the C3 and C5b-9 step, respectively. CD59 is considered critical for protecting erythrocytes from spontaneous complement attack, as deficiency of CD59 or CD59/DAF, but not of DAF alone, on human erythrocytes renders them sensitive to complement lysis in paroxysmal nocturnal hemoglobinuria syndrome. To evaluate the relative roles of CD59 and DAF in vivo, we have generated and studied a CD59 knockout and a CD59/DAF double-knockout mouse. CD59-deficient and CD59/DAF-double-deficient mouse erythrocytes were highly sensitive to antibody-induced complement lysis in vitro, yet neither CD59 knockout nor CD59/DAF double-knockout mouse developed spontaneous hemolytic anemia. Consistent with the latter observation, erythrocytes from the 2 strains of mutant mice were shown to have a normal lifespan in vivo. In contrast, mouse erythrocytes deficient in complement receptor 1 (CR1)-related gene y (Crry), a membrane C3 inhibitor with DAF and membrane cofactor protein activities, were rapidly eliminated from the circulation by a complement-dependent mechanism. Compared with DAF-deficient erythrocytes, Crry-deficient erythrocytes incurred higher levels of spontaneous C3 deposition in vivo. These findings demonstrate that CD59 and DAF are not indispensable on murine erythrocytes. Rather, effective C3 regulation on the cell surface, provided by Crry rather than DAF, is necessary for mouse erythrocytes to resist spontaneous complement attack. Our results raise the possibility that proper control of C3 activation may also be critical on human erythrocytes, where CR1 but not DAF could be the principal regulator of spontaneous C3 activation.
authors: Center for Experimental Therapeutics and Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
authors: Takashi
authors: T
authors: Miwa
authors: Lin
authors: L
authors: Zhou
authors: Brendan
authors: B
authors: Hilliard
authors: Hector
authors: H
authors: Molina
authors: Wen-Chao
authors: WC
authors: Song
mesh_terms: D000818:Animals; D018958:CD55 Antigens / Q000235:genetics / Q000502:physiology*; D018957:CD59 Antigens / Q000235:genetics / Q000502:physiology*; D002470:Cell Survival; D003167:Complement Activation; D003176:Complement C3 / Q000378:metabolism; D015938:Complement Membrane Attack Complex / Q000502:physiology; D003171:Complement Pathway, Classical; D019610:Cytoprotection; D004546:Elapid Venoms / Q000494:pharmacology; D004912:Erythrocytes / Q000166:cytology*; D018390:Gene Targeting; D007700:Kinetics; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000096:biosynthesis; D011951:Receptors, Complement / Q000502:physiology*; D017463:Receptors, Complement 3b
chemical_list: D018958:CD55 Antigens; D018957:CD59 Antigens; D003176:Complement C3; D015938:Complement Membrane Attack Complex; C081470:Cr1l protein, mouse; D004546:Elapid Venoms; D012333:RNA, Messenger; D011951:Receptors, Complement; D017463:Receptors, Complement 3b; C016310:cobra venom factor