Background: Rituximab (RIT) is effective as a part of the desensitization therapy before ABO-incompatible kidney transplantation (ABOi-KTx), and a single dose of RIT at 375 mg/m2 or less is recommended. However, adequate RIT dose recommendations have not yet been established for individual recipients. Therefore, we evaluated the relationship between the proportion of B cells in peripheral blood and acute antibody-mediated rejection (AAMR).
Methods: Forty-four consecutive ABOi-KTx recipients were enrolled in this retrospective study. Before transplantation, subjects were treated with RIT at various doses, ranging from 65 to 400 mg/body (46-263 mg/m2), followed by plasmapheresis and intravenous immunoglobulin as a desensitization therapy. The percentage of CD19+ cells in the total peripheral blood lymphocytes population (%CD19) was determined the day before transplantation. Transplant recipients were divided into 2 groups according to pretransplant %CD19, as follows: low %CD19 group, ≤ 1.2% (n = 35) and high %CD19 group, > 1.2% (n = 9). The relationship between %CD19 and incidence of AAMR was evaluated, and the predicting factors for AAMR incidence were determined by univariate and multivariate analyses.
Results: The incidence of AAMR was significantly higher in the high %CD19 group than in the low %CD19 group (44.4% vs 5.7%, P = .006). Furthermore, multivariate analysis showed that %CD19 > 1.2% was the only independent factor to predict AAMR, with an odds ratio of 14.31 (P = .038).
Conclusion: High %CD19 values after rituximab administration in ABOi-KTx recipients implies insufficient depletion of B cells, which can lead to AAMR.
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