Fibronectin from alpha 1,3-galactosyltransferase knockout pigs is a xenoantigen

Ray K. Chihara, Andrew J. Lutz, Leela L. Paris, Zheng Yu Wang, Richard A. Sidner, Alex T. Heyrman, Susan M. Downey, Christopher Burlak, A. Joseph Tector

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Background: Antibody-mediated rejection continues to be an obstacle for xenotransplantation despite development of α1,3-galactosyltransferase knockout (GTKO) pigs. Fibronectin (Fn) from GTKO pigs was identified as a xenoantigen in baboons. N-glycolylneuraminic acid (Neu5Gc), similar to galactose α1,3-galactose, is an antigenic carbohydrate found in pigs. We evaluated human antibody reactivity and performed initial antigenic epitope characterization of Fn from GTKO pigs. Materials and methods: GTKO pig aortic endothelial cells (AEC) were isolated and assessed for antibody-mediated complement-dependent cytotoxicity (CDC). Human and GTKO pig Fn were purified and analyzed using immunoblots. GTKO pig and human AEC absorbed human sera were assessed for CDC and anti-GTKO pig Fn antibodies. GTKO pig proteins were assessed for Neu5Gc. Immunoaffinity-purified human IgG anti-GTKO pig (hIgG-GTKOp) Fn using a GTKO pig Fn column were evaluated for cross-reactivity with other proteins. Results: GTKO pig AEC had greater human antibody binding, complement deposition and CDC compared with allogeneic human AEC. Human sera absorbed with GTKO pig AEC resulted in diminished anti-GTKO pig Fn antibody. Neu5Gc was identified on GTKO pig Fn and other proteins. The hIgG-GTKOp Fn cross-reacted with multiple GTKO pig proteins and was enriched with anti-Neu5Gc antibody. Conclusions: Removal of antigenic epitopes from GTKO pig AEC would improve xenograft compatibility. GTKO pig Fn has antigenic epitopes, one identified as Neu5Gc, which may be responsible for pathology and cross-reactivity of hIgG-GTKOp Fn. Genetic knockout of Neu5Gc appears necessary to address significance and identification of non-Neu5Gc GTKO pig Fn antigenic epitopes.

Original languageEnglish (US)
Pages (from-to)1123-1133
Number of pages11
JournalJournal of Surgical Research
Issue number2
StatePublished - Oct 2013


  • Antibody-mediated rejection
  • Fibronectin
  • N-glycolylneuraminic acid
  • Neu5Gc
  • Xenoantigen
  • Xenotransplantation

ASJC Scopus subject areas

  • Surgery


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