Prognostic Impact of Lymphocyte Subpopulations in Peripheral Blood after Hematopoietic Stem Cell Transplantation for Hematologic Malignancies

Background: We prospectively evaluated prognostic value of lymphocyte subpopulations in peripheral blood of allogeneic hematopoietic stem cell transplant (HSCT) recipients.

Methods: 113 allogeneic HSCT (47 sibling matched, 37 unrelated matched, 29 haploidentical)-performed patients diagnosed as AML (n = 66), ALL (n = 28), and MDS (n = 19) were prospectively enrolled. 14 lymphocyte subpopulations were quantified by flow cytometry of PB at specific time-points after HSCT, and their prognostic impacts were analyzed.

Results: At 1, 2, and 3 months post-HSCT, significant adverse impact on overall survival (OS) and/or event free survival (EFS) was exhibited by low levels of natural killer (NK) cells (≤32 and ≤90/µL at 1 and 2 months on OS and EFS); regulatory T cells (≤1/µL) on EFS at 2 months; and B cells (≤19 and ≤92/µL for OS and EFS at 3 months). At 12 months, low levels of T cells (≤1180/µL), helper/inducer (H/I) T cells (≤250/µL), cytotoxic/suppressor (C/S) T cells (≤541/µL), and NK cells (≤138/µL) were associated with significantly higher risk of relapse. Low levels of T cells (≤879/µL) and C/S T cells (≤541/µL), and high level of naïve thymic T cells (>115/µL) showed a significant association with poor OS; low levels of C/S T cells (≤541/µL) and NK cells (≤138/µL) showed a significant adverse impact on EFS.

Conclusions: Low levels of NK cells, regulatory T cells, and B cells at early stage post-HSCT are adverse prognostic indicators. At late stage, low levels of T cells and their subpopulations, NK cells, and high level of naïve thymic T cells are adverse prognostic indicators. © 2017 International Clinical Cytometry Society.