Early lymphocyte reconstitution is associated with improved transplant outcome after cord blood transplantation

Background aimsPrevious studies have shown that rapid recovery of the absolute lymphocyte count (ALC) is associated with improved transplant outcomes after related and unrelated donor allogeneic stem cell transplantation (allo-SCT). No consistent association has been reported between lymphocyte recovery and transplant outcome after cord blood transplantation (CBT)MethodsWe reviewed the records of 40 consecutive CBT patients at our institution to determine the impact of lymphocyte recovery on transplant outcomeResultsThe majority of patients (83%) received CBT for hematologic malignancies. Patients with ALC ≥150/μL at 30 days post-CBT had decreased non-relapse mortality (NRM) (P = 0.011) and improved survival (P = 0.013) compared with ALC < 150/μL. Patients with ALC < 100/μL at 30 days post-CBT had a significantly higher rate of graft failure than those with ALC ≥100/μL (four of 10 versus one of 29; P = 0.011). ALC was positively correlated with the nucleated cell dose and inversely correlated with the patient's age. There was no relationship between disease risk, type of conditioning regimen, anti-thymocyte globulin and number of cord units on ALC recoveryConclusionsOur results indicate that ALC 30 days post-CBT is a surrogate for engraftment, and that low ALC (<150/μL) identifies an ‘at-risk’ population of patients after CBT. Studies are needed to determine ways to increase ALC cell numbers post-CBT, including ex vivo-expanded natural killer cells using adoptive immunotherapy, which might improve outcome after CBT.