A transitional B-cell cytokine biomarker for risk stratifying renal transplant patients with borderline rejection.

Borderline allograft rejection can promote acute rejection and graft loss in some, but not all, patients. In this issue, Cherukuri et al. use a novel test based on peripheral blood transitional T1 B cells producing interleukin-10 and tumor necrosis factor-α, which identifies patients at high risk for poor outcomes. The potential mechanisms by which transitional T1 B cells might modulate alloreactivity need exploration, but following appropriate validation, this biomarker could risk stratify patients in need of early intervention.