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We have previously shown that human anti-pig antibodies include anti-GAl_-1-3GAL, Pk, and -Thomsen-Friedenreich (TF) antibodies. Purpose: To assess the expression of the Gal_l-3Gal, Pk and TF antigens on adult porcine pancreatic islets before and after collagenase digestion. Methods: Pancreases from 16 outbred adult White Large pigs (blood group A/O:2/14) were obtained from an abattoir. Each pancreas was digested by injecting a collagenase solution (Boehringer Mannheim Collagenase P, ~Img/ml, pH 7.4) into the main pancreatic duct followed by incubation for 20 mins at 37_C. After mechanical dispersion the unpurified islet preparation vas washed and fixed in formalin. Sections of pancreas before digestion were also fixed in formalin. All sections were then stained by immunohistology using human anti-Gal_l-3Gal antibody, human anti-Pk antibody (eluted from sepharose-Gal_l-3Gal and Pk immunoadsorbent columns respectively) and a mouse anti-TF monoclonal IgM Human kidney sections were used as negative controls. The presence of islets in the sections before and after digestion was confirmed by staining with an anti- insulin monoclonal antibody Results: There no Gal_l-3Gal, Pk and TF staining in human kidney sections The results for the islets arc shown in the table (expressed as staining before and after digestion of all 16 pancreases).
The Gal_l-3Gal, Pk and TF antigens were expressed in the intra-islet capillaries in the pancreas before digestion. In three animals the TF antigen was also expressed by islet cells Antigen expression was substantially reduced after collagenase digestion for all three antigens. The expression of the three antigens was similar in blood group A and 0 pigs. Conclusions: We have demonstrated expressioo of all three xenoantigens in pig pancreas The significantly reduced expression of Gal_3JGal, Pk and TF antigens on adult porcine pancreatic islets after collagenase digestion may increase the possibility of successful pig to human islet xenotransplantation.