Porcine and bovine cartilage transplants in cynomolgus monkey: II. Changes in anti-Gal response during chronic rejection.
The recent advances in avoiding hyperacute rejection by producing transgenic pigs with complement regulatory proteins call for the analysis of posttransplantation changes in anti-Gal activity in the absence of hyperacute rejection. Transplantation of cynomolgus monkeys with porcine or bovine meniscus and articular cartilage enabled the study of anti-Gal IgG response to xenografts that are not subjected to hyperacute rejection. The cartilage implants were kept in suprapatellar pouches of the recipients for 1 or 2 months and anti-Gal activity was measured in the serum at various time intervals after transplantation. Within 2 weeks after transplantation, titer of anti-Gal IgG, in all transplanted monkeys, increased by 20- to 100-fold, as measured in ELISA with synthetic alpha-galactosyl epitopes linked to bovine serum albumin or with mouse laminin. Furthermore, binding of serum anti-Gal to porcine endothelial cells increased by 10-fold or more after transplantation. Complement-mediated cytotoxicity also increased by two- to eightfold after transplantation. The elevated activity of anti-Gal was maintained for the 2-month period during which the grafts were kept in the monkeys, and returned to the pretransplantation level 6 months after graft removal. All these data suggest that the primate immune system responds vigorously to alpha-galactosyl epitopes on xenografts by activating many B lymphocytes that produce increased amounts of anti-Gal IgG, which may also be of high affinity. These antibodies are likely to bind to the xenograft cells, even if these cells express low numbers of alpha-galactosyl epitopes. Such antibody binding may play an important role in chronic rejection of xenografts.
Galili
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U
Department of Microbiology and Immunology, MCP-Hahnemann School of Medicine, Allegheny University, Philadelphia, Pennsylvania 19129, USA.
LaTemple
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DC
Walgenbach
A W
AW
Stone
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KR
D000818:Animals; D000906:Antibodies / Q000032:analysis; D002356:Cartilage / Q000637:transplantation*; D002417:Cattle; D004727:Endothelium / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology*; D006084:Graft Rejection / Q000276:immunology*; D007074:Immunoglobulin G / Q000032:analysis*; D008252:Macaca fascicularis; D051379:Mice; D013552:Swine; D014183:Transplantation, Heterologous / Q000276:immunology*; D014312:Trisaccharides / Q000276:immunology*
D000906:Antibodies; D000939:Epitopes; D007074:Immunoglobulin G; D014312:Trisaccharides; C076569:alpha-galactosyl epitope