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.