Original ResearchPublished 6 October 2026Clinical significance of persistent C4d deposition on sequential protocol biopsies in ABO-incompatible kidney transplantationYu Kijima · Hideki Ishida · Takafumi Yagisawa · Toshihito Hirai · Kohei Unagami · Tomokazu Shimizu · Toshio TakagiFrontiers in Nephrologydoi 10.3389/fneph.2026.1940137