title: Effect of tandem forms of DAF(CD55) on complement-mediated xenogeneic cell lysis.
abstract: BACKGROUND
  It is difficult to produce a transgenic animal with high expression of decay-accelerating factor (CD55: DAF) or other molecules. The purpose of this study was to assess the effect of tandem forms of DAF on a xenogeneic cell membrane against human complement.
  
  
  METHODS
  cDNAs of the delta-Short Consensus Repeat (SCR) 1-DAF, the double-DAF, the triple-DAF, and the tetra-DAF with a FLAG-tag were established. Chinese hamster ovary (CHO) cell lines and a pig endothelial cell (PEC) line expressing these molecules were established. The amelioration of complement-mediated lysis by the transfectant molecules on these cells was examined. The CHO cell transfectants were also incubated with normal human serum, and the amount of C3 deposited was determined by FACS analysis.
  
  
  RESULTS
  Stable CHO cells and PEC transfectants, in which each molecule was clearly expressed, and Western blots showed that each band corresponded to the expected molecular weight. The extent of amelioration of complement-mediated lysis by these four molecules was then examined. A clear tendency was found, as follows: The higher the tandem number of DAF, the greater was the effect on cytotoxicity. Additional experiments focusing on triple-DAF and tetra-DAF did not indicate any significant difference in complement-mediated lysis. Consistent with the complement-regulatory ability, the inhibitory effect of the deposition of C3 fragments by these molecules was closely related to the degree of amelioration.
  
  
  CONCLUSIONS
  These data indicate that tandem DAF, especially a triple-DAF, is a very effective form for protecting against complement activation.
authors.affiliation: Division of Organ Transplantation, Department of Molecular Therapeutics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan. miyagawa@orgtrp.med.osaka-u.ac.jp
authors.forename: Shuji
authors.initials: S
authors.lastname: Miyagawa
authors.forename: Daisuke
authors.initials: D
authors.lastname: Fukuta
authors.forename: Etsuko
authors.initials: E
authors.lastname: Kitano
authors.forename: Chizuko
authors.initials: C
authors.lastname: Kobayashi
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Fumimoto
authors.forename: Akio
authors.initials: A
authors.lastname: Shirasu
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Hattori
authors.forename: Ryota
authors.initials: R
authors.lastname: Shirakura
authors.forename: Masahiro
authors.initials: M
authors.lastname: Fukuzawa
mesh_terms: D000818:Animals; D018958:CD55 Antigens / Q000235:genetics / Q000494:pharmacology*; D016466:CHO Cells; D003167:Complement Activation / Q000187:drug effects*; D016384:Consensus Sequence; D006224:Cricetinae; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D018076:DNA, Complementary; D005434:Flow Cytometry; D012091:Repetitive Sequences, Nucleic Acid; D013552:Swine; D014162:Transfection; D014183:Transplantation, Heterologous / Q000276:immunology*
chemical_list: D018958:CD55 Antigens; D018076:DNA, Complementary