title: Carbohydrate antigens.
abstract: OBJECTIVE
  To summarize the current knowledge of carbohydrate antigens as related to xenotransplantation. The emphasis is on non-Gal carbohydrate antigens identified in many institutes. In addition, several topics such as glycosyltransferase-transgenic pigs, innate cell receptors and porcine endogenous retrovirus (PERV) will be discussed.
  
  
  RESULTS
  Studies related to iGb3 and neoantigens after knocking out GalT (GGTA1) were reviewed. Available data do not support the conclusion that GalT-KO remains iGb3 and/or that neoantigens are produced in the pigs. Concerning non-Gal antigen, in addition to the Hanganutziu-Deicher (H-D) antigen (NeuGc), Forrsman antigen, Galα1-3Lew(x), α-linked or β-linked GalNAc, β3 linked Gal, NeuAc, such as Neu5Acα2-3Galβ1-3GlcNAc, and Sid blood group (Sd(a))-like antigens are candidates. However, to date some of these remain controversial and others need further study to completely identify them. Regarding the H-D antigen, different from the α-Gal, it has a complicated expression system, but has cytotoxic effects toward pig cells. To modify other carbohydrate antigen apart from α-Gal, only the overexpression of GnT-III appears to have an effect on the suppression of the N-linked sugar of non-Gal antigen. Concerning innate cell receptors related to carbohydrates (ligands), the focus turned from natural killer (NK) receptor to others, such as monocytes. Finally, PERV contains a ligand with an N-linked sugar. Modification of the glycosylation pattern appears to be associated with regulating PERV infectivity.
  
  
  CONCLUSIONS
  A considerable amount of data related to carbohydrate antigens is now available. At the same time, however, discrepancies between studies complicate this issue. Further studies will be needed to completely understand this complicated area of interest.
authors.affiliation: Division of Organ Transplantation, Department of Surgery, Osaka University Graduate School of Medicine, Osaka, Japan. miyagawa@orgtrp.med.osaka-u.ac.jp
authors.forename: Shuji
authors.initials: S
authors.lastname: Miyagawa
authors.forename: Takehisa
authors.initials: T
authors.lastname: Ueno
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nagashima
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Takama
authors.forename: Masahiro
authors.initials: M
authors.lastname: Fukuzawa
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D000941:Antigens / Q000276:immunology*; D002241:Carbohydrates / Q000276:immunology*; D006801:Humans; D013552:Swine; D014183:Transplantation, Heterologous / Q000276:immunology*
chemical_list: D000941:Antigens; D002241:Carbohydrates