LAUSR

Background. The impact of newer approaches to haploidentical transplantation on Epstein–Barr virus (EBV) is largely unknown. Methods. We prospectively evaluated the incidence of EBV reactivation and its impact on transplantation outcomes in 71 patients undergoing haploidentical transplantation with posttransplantation cyclophosphamide in combination with CTLA4Ig-based T-costimulation blockade. Results. Eight patients developed EBV reactivation at a median of 96 days with no incidence of lymphoproliferative disorder. There was no impact of EBV reactivation on acute graft-versus-host disease (GVHD), nonrelapse mortality, progression-free, or overall survival. Despite an overall incidence of 19%, there was a significant increase in chronic GVHD following EBV reactivation (62.5% versus 8%; P = 0.01). NKG2Apos subset of CD56dim natural killer cells increased substantially and persisted following EBV reactivation and chronic GVHD, with a reciprocal decrease in NKG2Cpos subset, whereas the reverse was witnessed in those without chronic GVHD (P < 0.01). Increase in NKG2Cpos subset and a decrease in the NKG2Apos subset were witnessed within 3 months of subsidence of chronic GVHD. Conclusions. Thus, CTLA4Ig-based haploidentical transplantation was associated with a low incidence of EBV reactivation without EBV-lymphoproliferative disorder. However, EBV reactivation was associated with a sustained alteration in NKG2A and NKG2C subsets of CD56dim natural killer cells which might have a pathogenic role in chronic GVHD.