Long-term persistent lymphopenia in hematopoietic stem cell donors after donation for donor lymphocyte infusion

To analyze the consequences of lymphocyte donations on lymphopoiesis in donors having previously undergone hematopoietic stem cell collection for allogeneic stem cell transplantation.

Repeated analysis of leukocyte subsets in the peripheral blood of 76 hematopoietic stem cell donors undergoing lymphocyte donation(s) for DLI.

Grade I/II lymphopenia was present in 22 donors (29%) just before first apheresis for lymphocyte collection, demonstrating that former stem cell donation induced prolonged lymphopenia in a subset of donors. The monocytic lineage was not affected. Older age and history of PBSC harvest constituted 2 independent factors of lymphopenia, but had no influence on monocytopenia. The first apheresis induced lymphopenia in 36 donors (47%) and monocytopenia in 23 donors (39%). Lymphopenia before first apheresis and prior history of PBSC harvest were independent factors of apheresis-induced lymphopenia while those factors had no influence on monocytopenia. A time-dependent decrease in lymphocyte counts was observed in donors undergoing repeated aphereses, resulting in persistent and prolonged lymphopenia in 50% of donors. No persistent monocytopenia over time and aphereses was observed. Kaplan-Meier estimate of the risk to develop persistent lymphopenia after multiple aphereses was 21% +/- 6% at 2 months, 38% +/- 8% at 4 months, and 64% +/- 10% at 12 months. After Cox regression analysis, previous PBSC harvest remained the unique factor associated with the risk for persistent lymphopenia.

Monitoring the potential long-term effects of repeated aphereses in hematopoietic stem cell donors appears important. Selecting young bone marrow donors for subsequent DLI significantly reduces the risk for acute and prolonged lymphopenias.