[Introduction]

Rituximab (RTX) is used for desensitization in highly sensitized patients, such as those undergoing ABO-incompatible (ABOi) kidney transplantation. Although RTX is generally effective, some patients exhibit a poor sensitivity to RTX. However, the factors that contribute to low RTX sensitivity and subsequent rejection are unknown. We sought to identify the characteristics of patients with a low RTX sensitivity and the risk factors for rejection by comparing patients based upon RTX treatment.

[Materials and Methods]

From 2009 to 2017, 144 patients who underwent living kidney donor transplantation were enrolled in this retrospective study. RTX was administered to ABOi recipients 5 days prior to operation. In non-RTX treated patients, the percentage of CD19⁺ B cells among total peripheral blood lymphocytes was measured before transplantation (CD19%). In RTX-treated patients, CD19% before and after RTX treatment prior to operation (postRTX-CD19%) was determined. Antibody-mediated rejection and T-cell mediated rejection within 3 months of operation were evaluated. All patients were divided into CD19% high (CD19%>11%) or CD19% low (CD19%≤11%) groups. Those who received RTX were further divided into postRTX-CD19% high (postRTX-CD19%>1.0%) or postRTX-CD19% low (postRTX-CD19%≤1.0%) groups.

[Results]

In total, 95 recipients received RTX. Both groups had a similar frequency of rejection (17.8% and 16.3%, respectively). The mean dose of RTX was 239±98.1 mg/body (145±62.2 mg/m²) and was not found to be significantly different between recipients who did and did not experience rejection. Although CD19% did not affect the likelihood of rejection among recipients without RTX, recipients with a high CD19% (n=39) were more likely to develop rejection compared to recipients with a low CD19% (n=68) among patients who received RTX (chi-squared test, p<0.05). In addition, patients with a high postRTX-CD19% who received RTX (n=6) were also more likely to suffer from rejection compared to those with a low postRTX-CD19% (n=84) (chi-squared test, p<0.05). All recipients who had both a high CD19% and high postRTX-CD19% experienced rejection within 3 months.

[Conclusion]

For highly sensitized recipients, a high CD19% before or after RTX treatment is a risk factor for rejection. Those with both high CD19% before and after RTX administration should be carefully monitored since they may be more likely to develop rejection compared to other patients.

CITATION INFORMATION: Kono M., Shirakawa H., Wakai S. Elevated Levels of CD19⁺ B Cells before or after Rituximab Administration is a Risk Factor for the Early Rejection of a Living Kidney Transplant Am J Transplant. 2017;17 (suppl 3).

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