Expansion of NKG2C-expressing natural killer cells after umbilical cord blood transplantation in a patient with peripheral T-cell lymphoma with cytotoxic molecules

A 64-year-old woman presented with generalized lymphadenopathy and systemic manifestations. The examination of a biopsy specimen revealed peripheral T-cell lymphoma not otherwise specified (PTCL-NOS) expressing cytotoxic molecules. Umbilical cord blood transplantation was successful during a partial remission state after the administration of salvage chemotherapy. The donor-derived large granular lymphocytes started to increase as a result of cytomegalovirus reactivation. The fraction of natural killer (NK) cells expressing the NKG2C molecule accounted for one-third of the total lymphocytes for almost two years. We implicitly indicate the association between the persistence of donor-derived NKG2C⁺ NK cell-expansion and maintaining a complete remission in similar cases of aggressive PTCL-NOS.