IMMUNOMICROSCOPICAL LOCALIZATION OF HUMAN PREFORMED NATURAL ANTIBODIES AGAINST PIG-TISSUES IN XENOGENEIC TRANSPLANTATION

The targets of preformed natural antibodies need to be identified when ever the use of pig organs is considered for human transplantation. In this study we used extracorporeal perfusion of pig organs with human blood, immunocytological techniques and immune-electron microscopy to identify the targets and the nature of human preformed natural antibod ies against pig antigens. The antibodies were found to be mainly of th e IgG and IgM type and directed not only against endothelial cells, bu t also against mesenchymal and epithelial structures. To reproduce an in vivo situation, a Bio-pump was used to xenoperfuse pig kidneys and livers with human fresh oxygenated blood at 37 degrees C, drawn from p olycythaemic patients. Biopsies showed a deposition of human IgG and I gM on tubuli and glomeruli of pig kidneys and on endothelial cells of pig livers. Preperfusion of pig liver with human blood for 45 minutes before perfusion of kidneys significantly reduced the deposition of th e natural antibodies.