CD56+bright and CD56+dim natural killer cells in patients with chronic myelogenous leukemia progressively decrease in number, respond less to stimuli that recruit clonogenic natural killer cells, and exhibit decreased proliferation on a per cell basis

Abstract

Human natural killer cells (NK) require accessory cell-derived contact and soluble factors for maximal expansion. However, it is unclear whether increased recruitment of clonogenic NK, increased proliferation on a per cell basis, or a combination of both is responsible for the increased expansion. We show that expansion of both CD56+dim and CD56+bright NK from normal donors is increased in the presence of M2- 10B4 accessory cell-soluble factors. In contrast, the addition of M2- 10B4 stromal ligands further augments only the expansion of CD56+bright NK. Using single-cell sorting of CD56+bright NK, M2–10B4-soluble and contact factors independently increase both recruitment of clonogenic NK and proliferation on a per cell basis. This well-defined M2–10B4 accessory cell system was used to investigate potential defects in NK from patients with CML. Although we have previously shown diminished interleukin-2 (IL-2)-activated NK outgrowth and function from patients with chronic myelogenous leukemia (CML) as their disease progresses, it has been unclear if this is due to a defect in an accessory cell function or an inherent abnormality of CML NK themselves. CD56+/CD3- NK purified by fluorescence-activated cell sorting from 21 patients (7 early chronic phase [ECP] patients, 10 late chronic and accelerated phase [LCP/AP], and 4 blast crisis [BC] patients) were studied. The proliferative capacity, clonogenic frequency, and cytotoxic capacity of CML NK were compared with NK from normal donors. The absolute number of circulating NK per milliliter of peripheral blood is significantly decreased in patients with CML compared with normal donors (normal, 63,700 +/- 6,400; ECP, 40,700 +/- 6,700; LCP/AP, 31,900 +/- 6,000; BC, 10,700 +/- 5,200). Additionally, the unique CD56+bright NK subset, analyzed as a percentage of the total circulating NK pool, is significantly reduced in all patients with CML (normal, 5.7% +/- 0.8% v CML [all stages combined], 2.5% +/- 0.5%, P = .001]. After purification of NK to correct for differences in circulating NK number, resting NK cytotoxicity against K562 tumor targets is significantly reduced in patients with CML on or recently on hydroxyurea therapy. However, this reduced cytotoxicity can be corrected by 18 hours of incubation with 1,000 U/mL recombinant IL-2. When plated in limiting dilution on viable M2–10B4, which maximally stimulates NK from normal donors, we show that both NK clonogenic frequency and proliferative capacity are significantly reduced as CML progresses, demonstrating an inherent defect in their ability to respond to normal NK stimuli. Although NK cloning efficiency between normal donors and ECP CML patients was the same, significant differences were observed in (1) the absolute number of circulating CD56+/CD3- NK, (2) the absolute number of circulating CD56+bright NK, and (3) proliferation on a per cell basis. Unlike resting NK function, prior cytotoxic therapy alone did not account for these observed abnormalities. These data suggest that, although NK are not derived from the malignant clone, they are inherently affected by their malignant microenvironment.

Sustained upregulation of effector natural killer cells in chronic myeloid leukemia after discontinuation of imatinib

“…Previously reported results indicate that NK cells of patients newly diagnosed with CML are reduced in numbers or in proportion among lymphocytes and have limited cytolytic capacity at diagnosis of CML, and that these abnormalities persist during IM-induced remission. (39)(40)(41) The present results suggest that NK cells are more sensitive to the residual BCR-ABL-positive cells than are NKT cells and CD8 + T cells. However, the patterns in CD8 + T cells were different from those in NK cells among the four groups, implying that these two types of immune cells play different roles in CML tumor surveillance in different situations.…”

The naive T‐lymphocyte compartment is well preserved in patients with chronic myelogenous leukaemia in chronic phase

“…The phenotypic and functional abnormalities of the immune system of CML patients have been well described (Spiers et al , 1977; Dowding et al , 1984; Tsuda & Yamasaki, 2000). Several reports have suggested that NK cells decrease in number and function during the course of CML, and are restored in accordance with a reduction in white blood cell counts (Pierson & Miller, 1996; Guarini et al, 2001). In the present study, expansion of NK/T cells was observed in both CML groups, when compared with the healthy control subjects.…”

IL‐1β regulates a novel myeloid‐derived suppressor cell subset that impairs NK cell development and function

“…CD27, CD11b and KLRG‐1 expression divides peripheral NK cells into subsets and available data suggest that cells expressing only CD27 + to be less differentiated than CD27 + CD11b + NK cells, and cells expressing CD11b and KLRG1, but not CD27, may represent the most differentiated NK cells (reviewed in 24, 25). Patients with diverse types of cancer (such as myelogenous leukemia and lung carcinoma) present with NK cell defects, including reduced NK cell numbers, reduced NK cell activity or reduced expression of activating receptors by NK cells 26, 27. Although clinical studies and reports using mouse tumor models have described MDSC suppressing NK cell activities 18, 28, 29, the role of specific MDSC subsets on NK cell suppression remains unclear.…”