How Does ABO Antigen Expression Change Ten Years After Transplantation?
Ten years after transplantation, ABO antigen expression decreases significantly in an incompatible kidney allograft, whereas it remains stable in ABO-compatible transplants.
Based on research by Tanabe et al., the key changes and differences include:
- Significant Decrease in ABOi Grafts: In ABO-incompatible (ABOi) recipients, blood group antigen expression decreases to approximately 64% of the levels measured in the initial implantation biopsy.
- Stability in ABOc Grafts: In contrast, protocol biopsies of ABO-compatible (ABOc) recipients show that antigen expression remains almost perfectly stable at 99.8% after the same ten-year period.
- Biological Mechanisms: This long-term reduction in antigenicity is described as a decrease of blood type antigenicity. It is often associated with the concept of accommodation, where the donor organ continues to function despite the presence of circulating antibodies.
- Endothelial Changes: Some cases describe the development of blood-type chimerism in the renal endothelium, further altering how the recipient’s immune system perceives the graft.
Theoretical options to further reduce antigenicity — such as the use of recombinant galactosidase enzymes to “strip” antigens — have shown promise in laboratory settings but have not yet been clinically implemented.
