Influence of donor MHC class I antigen expression on graft survival after rat parathyroid allotransplantation

Abstract.

Background and aims: We investigated the influence of donor MHC antigen expression on graft survival after parathyroid transplantation in three different strain combinations. Methods: MHC class I and II expression on parathyroid tissue of Lewis (LEW), Dark Agouti (DA), and Wistar-Furth (WF) rats was first analysed semiquantitatively by immunohistochemistry. Additionally, five groups were transplanted: (1) LEW to LEW, (2) DA to DA, (3) LEW to DA, (4) WF to LEW, and (5) DA to LEW. Methods: MHC class I expression was strong in DA, moderate in WF, and weak in LEW rats; MHC class II expression was negative in all three strains. In the interstitium of all investigated tissue specimens, the proportion of MHC class II-expressing cells was low. Results: After syngeneic transplantation, graft survival could be documented over the whole observation period. A mean graft survival of 20 (±2) days was observed following transplantation from LEW to DA, grafts in the group WF to LEW were rejected after 13 (±1) days, and graft function lasted 8 (±2) days in the group DA to LEW. The number of intragraft leukocytes expressing MHC class II molecules was equal in all groups, whereas increased levels of MHC class I on rat parathyroid tissue before transplantation resulted in a more rapid rejection. Conclusion: These results demonstrate that immunogenicity of rat parathyroid tissue seems to be determined by the amount of MHC class I expressed on donor parenchymal cells.