Effect of induction therapy on peripheral blood lymphocytes after lung transplantation: A multicenter international study

Introduction: Lymphocytes, which are targeted by immunosuppressive therapies, may be influenced by induction and recipient characteristics. The objective of this study was to evaluate the influence of induction therapy on lymphocyte kinetics after lung transplantation (LTx) according to the recipient characteristics and allograft outcomes. Methods: We retrospectively collected total lymphocyte counts from peripheral blood, which was monitored before and after transplantation (days 7, 14, 30, 90, 180, 365 and 730) in patients from 3 different lung transplant centers in Europe who encountered different induction strategies (no induction, anti-thymocyte globulins and basiliximab). Results: A total of 164 recipients were included: 50 patients who did not receive induction therapy and 114 patients who received induction therapy (57 with anti-thymocyte globulins and 57 with basiliximab). The pre-transplant lymphocyte levels and induction therapy were associated with higher lymphocyte differences between pre-transplantation and day 7 (p <.001). The lymphocyte reconstitution was correlated with the pre-transplant weight (+10 cells/μL/kg, 95%CI [+5; +15], p < 0.001), pre-transplant lymphocyte level (−248 cells/μL, 95%CI [−368; −127] between low and high level recipients, p < 0.001), induction therapy with anti-thymocyte globulins (−636 cells/μL, 95%CI [−797; −475], p < 0.001), and induction with basiliximab (−641 cells/μL, 95%CI [−801; −481], p < 0.001) compared with no induction. Age was associated with a delayed reconstitution at day 30 (−9 cells/μL/year, 95%CI [−17; −1], p = 0.04) and day 90 (−8 cells/μL/year, 95%CI [−16; −1], p = 0.04). One-year mortality was associated with a lower lymphocyte count (−325 cells/μL, 95%CI [−522; −128], p = 0.001) and a best predictive threshold of 1000 cells/μL at day 90. Conclusion: The blood lymphocyte count after LTx is associated with the pre-transplant lymphocyte level, age, weight and induction therapy and predicts one-year mortality.