Variability of Cytotoxicity to Pig Cultured Cells and Its Determinant Factor in Human Sera

252

198

The first and major clinical obstacle in xenotransplantation is antibody-mediated hyperacute rejection. Although human natural antibodies against Galalpha1,3Gal (Gal) antigens, which are common on porcine cells and organs, have been identified to play a major role in hyperacute rejection, other natural antibodies against non-Gal epitopes may be also involved in the process. Here, we present evidence suggesting that the majority of human anti-non-Gal antibodies are specific for carbohydrate structures carrying terminally linked N-glycolylneuraminic acid (NeuGc), a xenoantigen existing in almost all animals except humans. Furthermore, this anti-NeuGc activity is detectable in 85% of healthy humans, implicating the involvement of NeuGc in hyperacute rejection and the importance of developing strategies for removing NeuGc for clinical xenotransplantation.

Section: Discussionmentioning

confidence: 99%

Anti‐N‐glycolylneuraminic acid antibodies identified in healthy human serum

Zhu¹,

Hurst²

2002

252

198

“…NeuGc antibodies has long been performed by ELISA using NeuGc-GM3 glycolipid purified from horse red blood cells (RBC) or high molecular weight bovine glycoproteins [13][14][15][16][17][18].…”

Section: Discussionmentioning

confidence: 99%

Are N‐glycolylneuraminic acid (Hanganutziu–Deicher) antigens important in pig‐to‐human xenotransplantation?

Miwa

Kobayashi

Nagasaka

et al. 2004

Carbohydrate structures on PRBC are different from those on PAEC. Healthy human sera contain anti-nonGal IgG antibodies to NeuGc expressed on PRBC, but not on PAEC. We speculate that anti-nonGal IgG antibodies to PRBC can recognize both NeuGc and protein, and this may be the reason why such antibodies have not been detected by ELISA. A definite conclusion about the immunogenicity of NeuGc has not been obtained. More sera from patients (not from non-human primates) sensitized with porcine cells or organs need to be studied.

“…There remains the problem, however, of non‐αGal xenoantigens. Although natural antibodies against NeuGc seem to be very rare [8,12] and thus would not cause hyperacute rejection at the time of transplantation, the possibility that H‐D antigens with NeuGc would elicit an immuno‐logical response has been indicated [2].…”

Section: Discussionmentioning

confidence: 99%

“…IgG and IgM antibody levels against H‐D antigens in sera of patients with porcine exposure history were measured by ELISA using GM3 (NeuGcα2–3 Galβ1–4 Glcβ1‐Cer)‐coated plates [8]. Briefly, 96‐well EIA/RIA microplates (Costar, Cambridge, MA, USA) were coated with 100 µl/well of 3 µg/ml of GM3 (NeuGc) in chloroform and methanol, which were completely evaporated at room temperature.…”

Section: Methodsmentioning

confidence: 99%

Lack of antibody production against Hanganutziu‐Deicher (H‐D) antigens with N‐glycolylneuraminic acid in patients with porcine exposure history

Kobayashi¹,

Yokoyama²,

Suzuki³

et al. 2000

The significance of non-alphagalactosyl antigens remains unclear in pig-to-primate xenotransplantation. Hanganutziu-Deicher (H-D) antigens with terminal N-glycolylneuraminic acid (NeuGc) are widely expressed on endothelial cells of mammalian species, with the exception of humans. As baboons and monkeys also express H-D antigens, a pig-to-non-human primate experimental model cannot resolve the question of whether H-D antigens can elicit a potent humoral response in human recipients. The purpose of this study was to elucidate the clinical significance of H-D antigens by examining the sera from patients who have been previously exposed to porcine tissue. After the digestion of porcine aortic endothelial cells (PAEC) by neuraminidase, NeuGc and N-acetylneuraminic acid (NeuAc) were quantitated by HPLC. IgG and IgM antibody levels against H-D antigens were measured by NeuGc-GM3-coated ELISA plates in the sera of patients who had undergone ex vivo kidney perfusion 1 to 3 weeks and 2 years previously (n=2) or had been injected with fetal porcine islets 2 months previously (n= 10). HPLC determined that 9.7x 10(7) NeuAc and 6.3x 10(7) NeuGc residues per cell were released from PAEC by neuraminidase, while 25.7x 10(7) NeuAc and an undetectable level of NeuGc were released from human aortic endothelial cells (HAEC). No significant elevation of IgG or IgM antibody levels against NeuGc-GM3 was observed in sera from patients with a history of porcine exposure. Considering the active production of antibody against the foreign galactosyl antigens after pig-to-human xenotransplantation, some production of antibodies against the equally foreign H-D antigens would be expected, because large amounts of NeuGc terminated saccharides are present in the pig endothelial cell surface. However, no production of antibodies directed to H-D antigens could be found in patients exposed to porcine tissue. Further studies are warranted to explain why H-D antigens do not elicit a significant antibody production.