High-dimensional mass cytometry analysis of NK cell alterations in Acute Myeloid Leukemia identifies a subgroup with adverse clinical outcome

Natural killer (NK) cells are major anti-leukemic immune effectors. Leukemic blasts have a negative impact on NK cell function and promote the emergence of phenotypically and functionally impaired NK cells. In the present work, we highlight an accumulation of CD56-CD16+ unconventional NK cells in acute myeloid leukemia (AML), an aberrant subset initially described as being elevated in patients chronically infected with HIV-1. Deep phenotyping of NK cells was performed using peripheral blood from patients with newly-diagnosed AML (N=48, HEMATOBIO cohort, NCT02320656) and healthy subjects (N=18) by mass cytometry. We evidenced a moderate to drastic accumulation of CD56- CD16+ unconventional NK cells in 27% of patients. These NK cells displayed decreased expression of NKG2A as well as the triggering receptors NKp30, and NKp46, in line with previous observations in HIV-infected patients. High-dimensional characterization of these NK cells highlighted a decreased expression of three additional major triggering receptors required for NK cell activation, NKG2D, DNAM-1, and CD96. A high proportion of CD56-CD16+ NK cells at diagnosis was associated with an adverse clinical outcome, with decreased overall survival (HR=0.13; P=.0002) and event-free survival (HR=0.33; P=.018), and retained statistical significance in multivariate analysis. Pseudo-time analysis of the NK cell compartment highlighted a disruption of the maturation process, with a bifurcation from conventional NK cells toward CD56-CD16+ NK cells. Overall, our data suggest that the accumulation of CD56-CD16+ NK cells may be the consequence of immune escape from innate immunity during AML progression.SignificanceThis work provides the first report of accumulation of unconventional CD56-CD16+ NK cells in non-virally induced malignancies. Pseudotime analysis highlights a bifurcation point occurring during the course of NK cell maturation, providing elements regarding the possible origin of CD56-CD16+ NK cells. Increased frequency of CD56-CD16+ NK cells is associated with adverse clinical outcome in AML and might contribute, as well as other maturation defects, to a defective control of AML progression. Overall, accumulation of CD56-CD16+ NK cells could be an important feature of immune escape from innate immunity.Graphical abstractKey pointsA disruption in the maturation process of NK cells leads to accumulation of unconventional CD56- CD16+ NK cells in patients with AMLHigh frequency of CD56-CD16+ NK cells is associated with adverse clinical outcome