The proportion of CD19+CD24hiCD27+ regulatory B cells predicts the occurrence of acute allograft rejection in liver transplantation.

BACKGROUND: Regulatory B cells (Bregs) play an essential role in inflammation and transplant tolerance. Several studies have reported a decreased number of Bregs in renal transplant patients with graft rejection. However, little is known about their role in the liver alloresponse. METHODS: To investigate whether the circulating Bregs have been associated with acute allograft rejection (AR) in liver transplantation patients, 19 patients receiving liver allografts from donation after cardiac death (DCD) donors were retrospectively studied. RESULTS: The postoperative proportions of circulating CD19+CD24hiCD38hi transitional Bregs (tBregs) and CD19+CD24hiCD27+ memory Bregs (mBregs) in patients diagnosed with AR (AR group) and other patients with stable allograft liver function (SF group) were evaluated using flow cytometry (FCM) analysis. Results showed that while no significant changes were found regarding both the tBreg and mBreg, proportions across all time points in the SF group, the AR group showed significantly decreased proportions of mBregs. All of the five AR patients responded fine to the treatments, and the proportions of mBregs increased significantly after anti-rejection therapies. In addition, AR was suspected in four recipients, but gradually they were diagnosed with hemolytic or obstructive jaundice and showed no decrease in the proportion of mBregs. CONCLUSIONS: For the first time, our results suggested the potential role of a decreased proportion of circulating mBregs in predicting AR in patients with post liver transplantation.