Distribution of non-gal antigens in pig cornea: relevance to corneal xenotransplantation.
OBJECTIVE
The aim of this study was to investigate the distribution of antigens other than galactose-α-1,3-galactose (Gal) (non-Gal) recognized by human and rhesus monkey serum antibodies in the α-1,3-galactosyltransferase gene-knockout (GTKO) pig cornea.


METHODS
The distribution of non-Gal, specifically N-glycolylneuraminic acid (NeuGc), in the corneas from wild-type (WT) and GTKO pigs was identified. Corneal sections from WT and GTKO pigs were incubated with human or rhesus monkey serum to determine immunoglobulin (Ig)M and IgG binding to corneal tissue by means of fluorescent microscopy.


RESULTS
Strong expression of NeuGc was found in all layers of both WT and GTKO pig corneas. In both humans and monkeys, antibody binding (IgG > IgM) to GTKO was found to be weaker than that to entire WT pig corneas, but in both, most antibody binding, especially IgG, was to the epithelium. There was weak diffuse antibody binding, especially of IgG, to the corneal stroma, suggesting binding to antigens expressed on collagen. There was no or minimal binding of IgM/IgG to the corneal endothelium.


CONCLUSIONS
Although the cornea is avascular, antibodies in primate serum can bind to pig antigens, especially on epithelial cells and stromal collagen. Although the binding to entire GTKO corneas was weaker than that to WT corneas, deletion of the expression of NeuGc and expression of human complement-regulatory proteins in the pig cornea will be important if prolonged clinical corneal xenograft survival is to be achieved.
*Department of Surgery, Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA; †Department of Pathology, University of Pittsburgh, Pittsburgh, PA; and ‡Revivicor, Inc, Blacksburg, VA.
David
D
Cohen
Yuko
Y
Miyagawa
Ruhina
R
Mehra
Whayoung
W
Lee
Kumiko
K
Isse
Cassandra
C
Long
David L
DL
Ayares
David K C
DK
Cooper
Hidetaka
H
Hara
D000328:Adult; D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism; D001324:Autoantigens / Q000378:metabolism*; D001666:Binding Sites, Antibody; D003315:Cornea / Q000378:metabolism*; D016039:Corneal Transplantation; D004187:Disaccharides / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D005700:Galactosyltransferases / Q000235:genetics; D055786:Gene Knockout Techniques; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D007075:Immunoglobulin M / Q000276:immunology; D008253:Macaca mulatta; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D009438:Neuraminic Acids / Q000378:metabolism*; D013552:Swine; D014019:Tissue Donors; D014183:Transplantation, Heterologous
D001324:Autoantigens; D004187:Disaccharides; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D009438:Neuraminic Acids; C032592:N-glycolylneuraminic acid; C055075:galactosyl-(1-3)galactose; D005700:Galactosyltransferases; C530267:alpha-1,3-galactosyltransferase 1, porcine