EVIDENCE OF HUMAN NON-ALPHA-GALACTOSYL ANTIBODIES INVOLVED IN THE HYPERACUTE REJECTION OF PIG LUNGS AND THEIR REMOVAL BY PIG ORGAN PERFUSION

Background: Human natural xenoantibodies represent a major hurdle to t he clinical application of pig lungs in transplantation by initiating hyperacute rejection within minutes to hours. Objective: The object wa s to compare pig organ perfusion and specific depletion of anti-alpha- galactosyl xenoantibodies for prevention of hyperacute rejection in th e pig to human lung combination. Methods: Large White pig (20-25 kg) l eft lungs were removed and continuously ventilated and reperfused ex v ivo either with (1) whole human blood previously perfused in situ thro ugh pig right lung (group I), liver (group II), or spleen (group III) or with (2) human plasma in vitro immunoabsorbed on columns containing alpha-galactosyl disaccharide (Gal-alpha-(1-3)Gal-beta-(CH2)(3)NH2; B disaccharide) (group IV). Each study group included 6 animals. Result s: The in situ and in vitro preperfusions depleted anti-alpha-galactos yl xenoantibodies and all in situ perfused pig organs showed histologi c signs of hyperacute rejection. After the ex vivo reperfusion, group I xenografts had a significantly (P < .001) longer functional and hist ologic survival than did xenografts in groups LI, III, and IV! Human b lood reperfusing group I xenografts had a significantly (P < 0.05) low er (1) decline of clotting factors and total circulating immunoglobuli ns, (2) total and membrane attack complex (C5b,6,7,8,9) complement act ivation, and (3) hemolysis. By Western blot analysis, the in situ lung preperfusion removed antibodies against non-alpha-galactosyl proteins of low molecular weight that were not eliminated by the alpha-galacto syl column. Conclusions: Results demonstrate that specific depletion o f anti-alpha-galactosyl antibodies alone incompletely protects pig lun gs from hyperacute rejection. It is speculated that the more complete prevention of this rejection afforded by pig lung preperfusion relates to the removal of other, non-alpha-galactosyl antibodies.