Time-dependent blood eosinophilia count increases the risk of kidney allograft rejection.

Background: Growing evidence suggest that type 2 immune effectors play a role in solid organ transplantation. The aim of this study was to evaluate the impact of blood count eosinophils (BCEo) on immunological outcomes in kidney transplant recipients with stable graft function after 3 months post-transplant.

Method: We performed cause-specific Cox model considering BCEo, the use of calcineurin inhibitors and systemic corticoids as time-dependent explicative variables on a prospective cohort of 1013 kidney transplant patients who experienced kidney allograft rejection and/or the appearance of de novo donor specific antibodies after excluding common causes of increased BCEo..

Findings: BCEo ≥ 0.3 G/L was associated with a 3-fold increased risk of rejection independent of immunosuppressive regimen after 3 months post-transplant in patients without pre-transplant DSAs and with CNI-based immunosuppression. No association between BCEo either with donor specific antibodies or graft survival was noticed.

Interpretation: These observations in this large cohort support the hypothesis of eosinophils in allo-immunity in human and claim for further mechanistic research.

Funding: This study was supported by the French National Research Agency, The "Institut de Recherche en Santé Respiratoire des Pays de la Loire" and the University hospital of Nantes.