Major transplantation antigens of pig kidney and liver. Comparisons between the whole organs and their parenchymal constituents.

We have previously shown that cultured renal and hepatic parenchymal cells of the pig differ in the expression of major transplantation antigens. Antigens apparently analogous to those of the mouse I region were detectable on kidney and some peripheral blood lymphocytes but not on liver, platelets, or other peripheral blood lymphocytes. The present study confirms these findings for liver parenchymal cells and for a mixture of kidney tubules and glomeruli prepared from fresh, perfused whole organs. However, homogenates prepared at the same time from the perfused whole organs showed no antigenic disparity. Whole liver homogenate contains I region analogues that are barely detectable on the parenchymal cell membrane. Liver parencymal cells may possess such antigens in a form not patnetly expressed, or the antigens may belong to other types of cell resident in the liver which are not removed by extensive perfusion. Similar results were obtained with liver homogenates derived from an orthotopic transplant to a fully allogeneic recipient and resident for 37 days, suggesting that blood lymphocytes persisting in the normal liver after perfusion could not account for these findings.