A study of the xenoantigenicity of adult pig islets cells.
BACKGROUND
The pig pancreas is considered to be the most suitable source of islets for xenotransplantation into patients with type I diabetes. The purpose of this study was to assess the antigenicity of pig islets, including the Galalpha1-3Galbeta1-4GlcNAc-R (the alpha-Gal) and Hanganutziu-Deicher (H-D) antigens, and the pathway involved in human complement activation.


METHODS
The expression of alpha-Gal on islets from adult pigs was investigated by immunohistochemical staining and flowcytometric analysis. The alpha1,3 galactosyltransferase (alpha1,3GT) activity of islets was determined by high-performance liquid chromatography. Antigenicity to human natural antibodies, including the H-D antigen of pig islets was next examined by treatment of pig islets with tunicamycin, D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP) and/or neuraminidase. In addition, complement-mediated islets lysis was examined using factor D-deficient and C1-deficient sera.


RESULTS
Adult pig islets expressed negligible amounts of alpha-Gal epitope, and alpha1,3GT activity was also undetectable. However, human natural antibodies, immunoglobulin G and M, and the anti H-D antibody react to the adult islet. Treatment of pig islets with tunicamycin, but not PDMP, led to a drastic reduction in antigenicity to human serum, indicating the importance of N-linked sugars on the islets. Neuraminidase treatment indicated the presence of, not only the H-D antigen, but also other sialic acid antigens that reacted with the human natural antibody. The complement deposition of C4, C3 and factor B on islets was demonstrated. The alternative pathway-mediated pig islet killing accounted for approximately 30% of that by the total complement pathway.


CONCLUSIONS
The origin of antigenicity of pig islets is mainly N-linked sugars including sialic acid antigens, but not the alpha-Gal, and pig islets can be injured by both the classical and the alternative complement pathway in human serum.
Komoda
Hiroshi
H
Division of Organ Transplantation, Department of Regenerative Medicine, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
Miyagawa
Shuji
S
Kubo
Tomoko
T
Kitano
Etsuko
E
Kitamura
Hajime
H
Omori
Takeshi
T
Ito
Toshinori
T
Matsuda
Hikaru
H
Shirakura
Ryota
R
D000017:ABO Blood-Group System; D000818:Animals; D015478:Antigens, Heterophile / Q000276:immunology*; D002469:Cell Separation; D004187:Disaccharides / Q000276:immunology; D005700:Galactosyltransferases / Q000032:analysis; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000276:immunology*; D009439:Neuraminidase / Q000494:pharmacology; D013552:Swine; D014415:Tunicamycin / Q000494:pharmacology
D000017:ABO Blood-Group System; D015478:Antigens, Heterophile; D004187:Disaccharides; D014415:Tunicamycin; C055075:galactosyl-(1-3)galactose; D005700:Galactosyltransferases; C047006:N-acetyllactosaminide alpha-1,3-galactosyltransferase; D009439:Neuraminidase