title: CD59 homologue regulates complement-dependent cytolysis of rat Schwann cells.
abstract: Antibody (Ab) sensitized sciatic nerve Schwann cells (SchC) of 2-day-old rats (SchC/2d) were significantly more susceptible to cytolysis by both heterologous, guinea pig (GP), and homologous rat serum complement (40 +/- 3.8% and 21.2 +/- 3.1%, respectively) than SchC of 6-day-old rats (SchC/6d) (7.9 +/- 5.9% and 2.6 +/- 3.1%, respectively). To determine if resistance to complement (C)-mediated cytolysis correlated with expression of membrane proteins which regulate C activation, we used Western blot and FACS analysis. Binding of specific polyclonal Ab demonstrated similar concentrations of Crry, a regulator of C3 convertase formation, on plasma membranes of SchC 2d and 6d. During C activation, both C3b deposition and iC3b formation were greater on SchC/6d than on SchC/2d and the C3b deposition did not correlate with enhanced cytolysis. In contrast, 2.1-fold more rat CD59, a regulator of C8 and C9 incorporation into C5b-9, detected with Western blot on SchC/6d compared with SchC/2d was confirmed by FACS. Further, both rat and GP C8/C9 lysed SchC/2d expressing human C5b-7 (20.1 +/- 3.7 and 21.6 +/- 4.7%, respectively), while only GP C8/C9 caused cytolysis of 10.7 +/- 4.3% SchC/6d expressing hu C5b-7 and rat C8/C9 did not (0.5 +/- 0.5%). Preincubation of SchC/6d with an F(ab)2 fragment of an mAb to rCD59 with blocking capacity, increased cytolysis mediated by rat serum C more than 6-fold to 16.7 +/- 3.0% but only 1.7-fold (maximum cytolysis 37.4 +/- 11.2%) in SchC/2d. Our data suggest that expression of rat CD59 on SchC increased almost two-fold between postnatal days 2 and 6, and this increased expression on more terminally differentiated SchC is a significant factor in regulating terminal complement complex formation and limiting cytolysis of rat SchC by homologous serum complement.
authors.affiliation: Department of Neurology, School of Medicine, University of Maryland at Baltimore 21218 USA.
authors.forename: S
authors.initials: S
authors.lastname: Sawant-Mane
authors.forename: S J
authors.initials: SJ
authors.lastname: Piddlesden
authors.forename: B P
authors.initials: BP
authors.lastname: Morgan
authors.forename: V M
authors.initials: VM
authors.lastname: Holers
authors.forename: C L
authors.initials: CL
authors.lastname: Koski
mesh_terms: D000818:Animals; D000954:Antigens, Surface; D018957:CD59 Antigens / Q000502:physiology*; D002478:Cells, Cultured; D003176:Complement C3 / Q000378:metabolism; D003185:Complement C8 / Q000378:metabolism; D003186:Complement C9 / Q000378:metabolism; D015938:Complement Membrane Attack Complex / Q000378:metabolism*; D003165:Complement System Proteins / Q000502:physiology*; D003602:Cytotoxicity, Immunologic; D006168:Guinea Pigs; D051381:Rats; D017207:Rats, Sprague-Dawley; D011956:Receptors, Cell Surface; D011951:Receptors, Complement / Q000378:metabolism; D012583:Schwann Cells / Q000276:immunology*; D012584:Sciatic Nerve
chemical_list: D000954:Antigens, Surface; D018957:CD59 Antigens; D003176:Complement C3; D003185:Complement C8; D003186:Complement C9; D015938:Complement Membrane Attack Complex; C513105:Cr1l protein, rat; D011956:Receptors, Cell Surface; D011951:Receptors, Complement; D003165:Complement System Proteins