Interpreting CD56+ and CD163+ Infiltrates in Early versus Late Renal Transplant Biopsies

Abstract

Background: CD56+ and CD163+ cell infiltration in human kidney transplant biopsies have not been fully evaluated. Methods: We investigated the association of CD56+ and CD163+ cell infiltration with human kidney transplant biopsies with antibody- or T-cell-mediated rejection (TCMR) and other histologic lesions. One hundred and seventy four clinically indicated transplant biopsies were included in this analysis. Immunohistochemical staining for C4d, CD56 and CD163 was performed. Results: One hundred and seventy four indication biopsies were divided into early (≤1 year posttransplant; n = 49) and late (>1 year posttransplant; n = 125) biopsies. High numbers of CD56+ cells were uncommon in early biopsies except for those with antibody-mediated rejection (AMR) only. On the other hand, high numbers of CD56+ cells were observed in late biopsies diagnosed as TCMR only, AMR only, and TCMR combined with AMR. In early biopsies, both CD56+ and CD163+ infiltrates correlated strongly with interstitial inflammation, tubulitis, and peritubular capillaritis (ptc) scores. The ci and ct scores, however, were correlated only with the number of CD56+ cells. In late biopsies, on the other hand, the number of CD56+ infiltrates was correlated only with ptc, while the number of CD163+ infiltrates was weakly correlated with any histologic lesion. Multivariable analyses showed that chronic active AMR and the number of CD56+ cells/10 HPF were independently associated with death-censored graft failure post-biopsy. The number of CD163+ cells was not correlated with any pathologic lesion and post-biopsy graft failure. CD56+ infiltrates were also associated with interstitial fibrosis and tubular atrophy. Conclusions: Intragraft CD56+ cell infiltrates were significantly associated with AMR and subsequent poor clinical outcomes.