Different sensitivity of rituximab-treatment to B-cells between ABO-incompatible kidney and liver transplantation.

A desensitization protocol with rituximab is currently widely used for kidney transplantation (KT) and liver transplantation (LT) across the ABO blood group-incompatible (ABO-I) barrier. However, it remains to be elucidated whether rituximab is equally effective for B-cell and T-cell immune responses in both KT and LT recipients. To clarify these effects of rituximab, we enrolled 46 KT and 77 LT recipients in this study. The proportion of peripheral blood B-cells was determined at the perioperative period. T-cell responses to allostimulation were evaluated by a mixed lymphocyte reaction (MLR) assay. One week after rituximab administration, peripheral B-cells became undetectable in ABO-I KT recipients but remained detectable in some of the ABO-I LT recipients; B-cells were undetectable in both groups by week 2. B-cells remained below the detection limit throughout the first year in the ABO-I KT recipients, whereas they reappeared in the periphery after 6months in the ABO-I LT recipients. There were no significant differences in alloreactive T-cell responses based on MLR analyses between ABO-I and ABO-compatible groups. This study indicates that rituximab has differing B-cell sensitivity between KT and LT recipients and a minimal effect on the alloreactive T-cell responses in KT and LT recipients.