title: Complement-inhibiting activities of human CD59 and analogues from rat, sheep, and pig are not homologously restricted.
abstract: Human erythrocyte CD59 and analogues isolated from erythrocytes of rat, sheep, and pig were examined for their ability to protect erythrocytes from various species against lysis by C from homologous and heterologous sources. In all cases, incorporation of human CD59 or analogues from rat, sheep, and pig efficiently protected guinea pig erythrocytes against lysis by C homologous with the CD59. However, each of the CD59 analogues also conferred on guinea pig erythrocytes protection against C from most heterologous species. These results demonstrate that none of the CD59 analogues tested were species specific in their C-inhibiting activity. Erythrocytes from species other than guinea pig could not be protected by incorporation of any of the available CD59 analogues despite similar incorporation in all erythrocytes tested. We suggest that the presence of endogenous inhibitors on these other erythrocytes masks the activity of incorporated CD59. Evidence that is supportive of this hypothesis was provided by demonstrating that blocking the endogenous CD59 with mAbs rendered erythrocytes susceptible to inhibition by high dosages of incorporated CD59.
authors.affiliation: Department of Medical Biochemistry, University of Wales College of Medicine, Heath Park, Cardiff, United Kingdom.
authors.forename: C W
authors.initials: CW
authors.lastname: van den Berg
authors.forename: B P
authors.initials: BP
authors.lastname: Morgan
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000494:pharmacology*; D018957:CD59 Antigens; D003169:Complement Inactivator Proteins / Q000494:pharmacology*; D015938:Complement Membrane Attack Complex / Q000037:antagonists & inhibitors*; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D051381:Rats; D012756:Sheep; D013045:Species Specificity; D013552:Swine
chemical_list: D015703:Antigens, CD; D018957:CD59 Antigens; D003169:Complement Inactivator Proteins; D015938:Complement Membrane Attack Complex; D008562:Membrane Glycoproteins