Mycophenolate mofetil suppresses the production of anti-blood type anitbodies after renal transplantation across the abo blood barrier: ELISA to detect humoral activity.

BACKGROUND

The introduction of novel immunosuppressive drugs has made it possible to achieve dramatic improvement in graft survival rates. In particular, the current immunosuppressive regimen including mycophenolate mofetil (MMF) has yielded excellent results including a nearly 100% 1-year graft survival rate at our institution in 2001. We used enzyme-linked immunosorbent assay (ELISA) to analyze humoral activity after ABO-mismatched renal transplantation using the MMF regimen.

METHODS

The patient received an ABO-mismatched graft from a living related sibling. Preoperatively, he underwent plasma exchange (PEX) and double-filtration plasmapheresis (DFPP) several times to remove anti-blood type antibodies. Mycophenolate mofetil was used as one of the induction regimens, but a switch was made to other drugs because of persistent gastrointestinal tract discomfort. Mycophenolate mofetil was restarted, however, because of graft dysfunction caused by severe humoral rejection. Humoral activity in this patient was investigated by ELISA during the postoperative follow-up.

RESULTS

Anti-blood type antibody immunoglobulin (Ig) M and IgG decreased immediately before the operation because of repeated PEX and DFPP. Both IgM and IgG were postoperatively stable and graft function was excellent. However, after switching from MMF to mizoribine (MZ), renal graft function gradually deteriorated, and the deterioration was associated with elevation of anti-blood type antibody, predominantly IgG. IgM antibody production was parallel to that of IgG, but was weaker. The elevated activity of anti-blood type antibody IgG decreased to the normal level as renal function recovered after MMF was restarted.

CONCLUSIONS

Anti-blood type antibody IgG decreased after the administration of MMF after ABO-mismatched renal transplantation, and it increased after withdrawal of MMF. MMF seems to affect B-cell populations that produce anti-blood type antibodies after renal transplantation across the blood barrier.