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

Abstract

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

Methods113 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.

ResultsAt 1, 2, and 3months 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/mu L at 1 and 2months on OS and EFS); regulatory T cells (1/mu L) on EFS at 2months; and B cells (19 and 92/mu L for OS and EFS at 3months). At 12months, low levels of T cells (1180/mu L), helper/inducer (H/I) T cells (250/mu L), cytotoxic/suppressor (C/S) T cells (541/mu L), and NK cells (138/mu L) were associated with significantly higher risk of relapse. Low levels of T cells (879/mu L) and C/S T cells (541/mu L), and high level of naive thymic T cells (˃115/mu L) showed a significant association with poor OS; low levels of C/S T cells (541/mu L) and NK cells (138/mu L) showed a significant adverse impact on EFS.

ConclusionsLow 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 naive thymic T cells are adverse prognostic indicators.