Background: ABOI kidney transplantation is an inevitable option to overcome organ shortage. Outcome of ABOI grafts improved and became equivalent to compatible grafts. There were few data on success rates of ABO antibody removal or relating to patients in who antibody removal fails. The purpose of this study was to evaluate the likelihood of achieving transplantation depending on ABO antibody titers.

Methods: 55 patients were enrolled between 2007-2012. We perform ABOI kidney transplantation using anti-CD20 antibody, tacrolimus and PP with IVIG. The median antibody titer was 1:64 (Range 8-4096). Transplantation was proceeded when the ABO titer reached ≤ 1:8. To determine the likelihood of achieving transplantation, the number of PP required to proceed transplantation and baseline ABO titer were analyzed.

Results: All 55 patients(100%) successfully completed transplantation after 5.75±4.3 PP with IVIG. Three patients did not reach target ABO titer and their achieved ABO titers at the time of transplantation were 1:16. (initial ABO titer were 1:256 in one patient, 1:2048 in one patient, and 1:1024 in one patient)

The median follow-up duration was 18.1 month (Range 0.9-71.8). The median ABO titer was 2 (Range 1-16) at the time of transplantation, 4(Range 1-64) at 1month posttransplantation and 4 (Range 4-128) at the last follow-up, respectively. The number of PP to reach an ABO titer of ≤ 1:8 was significantly correlated with baseline ABO IgG titers (r²=0.829, P < 0.001).

Conclusions: All 55 patients successfully preformed ABOI kidney transplantation without failure to achieve transplantation. Three patients even failed to reach target titer at the time of transplantation, however, all of them were successfully transplanted. Optimal ABO titer at the time of transplantation remains debatable, therefore we might carefully need to tailor our protocol with increasing cut-off ABO titer of 1:16. ABOI transplantation would be an accepted method of expanding kidney donor pool.

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