Late-onset neutropenia (LON) after low-dose rituximab treatment in living related kidney transplantation--single-center study.

We have performed more than 200 ABO-incompatible and HLA-incompatible transplantations, by using low-dose rituximab (Rit) as one of the B cell-depleting strategies. It has been revealed that a significant number of such patients who receive rituximab treatment develop late-onset neutropenia (LON). To obtain insights into the mechanism underlying the development of LON, we evaluated the kinetics of various cytokines involved in B-cell and granulocyte homeostases. The subjects of this study could be categorized into five groups, as follows; group 1: Rit(+)LON(+), N=22; group 2: Rit(+)LON(-), N=30; group 3: Rit(-)LON(+), N=15; group 4: Rit(-)LON(-), N=53; and group5: CKD5 patients (N=10). Serum levels of the cytokines were examined pre-RTx, 6months after RTx, 12months after RTx and 1.5years after RTx. We investigated the association between the serum levels of the B cell-related cytokines and the incidence of acute rejection. Serum levels of BAFF were significantly elevated in groups 1, 2 and 3; in particular, group 1 patients showed marked elevation of the serum BAFF at 6 and 12months after RTx. No correlations were observed between the serum BAFF and the incidence of acute rejection. Transplant recipients treated with low-dose Rit and presenting with LON showed a marked elevation of the serum BAFF levels.