T cell–mediated rejection (TCMR) is evidence of alloimmune reactivity characterized by inflammation within the tubules, interstitial space, and/or arterial intima and media in kidney transplantation. Risk factors for TCMR include younger recipient age, delayed graft function, inadequate immunosuppression, and HLA mismatch.1-6 Advances in genetics and 3-dimensional modeling have led to a renaissance in human leukocyte antigen (HLA) mismatch assessment through the evaluation of such mismatches at the molecular level.