DISTRIBUTION OF THE Gal??1???3Gal ANTIGEN IN CULTURED ADULT AND FETAL PORCINE PANCREATIC ISLET CELLS: AN IMMUNOELECTRON MICROSCOPIC STUDY1

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Abstract
The distribution of the Galα1–3Gal antigen (Galα) in cultured adult porcine islets (API) and fetal porcine pancreatic islet-like cell clusters (ICC) was studied using immunoelectron microscopy. API and ICC were cultured for 1 and 5 days, respectively, and immunogold labeled using human affinity isolated anti-Galα1–3Gal antibody, GS-IB 4 lectin and antibodies against islet pancreatic hormones, vimentin, and von Willebrand factor. Differentiated endocrine cells were Galα-negative, but, in ICC, some immature endocrine cells were slightly Galα-positive. The Galα-expression in API was much weaker compared to ICC. In both API and ICC, the Galα antigen was expressed on duct epithelial cells, acinar cells, and endothelial cells. In ICC, strong Galα expression was observed on flattened cells covering their surfaces. These cells were identified as centroacinar cells originating from intra-islet ducts. In conclusion, although mature endocrine cells of cultured API and ICC lack the Galα-xenoantigen, several other cellular compounds are strongly Galα positive, which may contribute to xenorejection of these grafts.