CD56⁺ILC1-like cell cytotoxicity is impaired in AML patients at diagnosis. (A) TRAIL, NKp30, and NKp80 expression in CD56⁺ ILC1-like cells and cNKs in HDs (CD56⁺ ILC1-like: n = 12-18, cNKs: n = 11-15) and AML patients at diagnosis (CD56⁺ ILC1-like: n = 11-20, cNKs: n = 8-10) by extracellular flow cytometry. (B) Intracellular flow cytometry was performed using PBMCs from AML patients at diagnosis to assess granzyme A (n = 4), granzyme B (n = 4), granzyme K (n = 4), perforin (n = 4), and granulysin (n = 7) expression in the CD56⁺ ILC1-like cells and cNKs. The results are compared with the values obtained in the HDs. (C-D) CD107a expression in CD56⁺ ILC1-like cells is assessed by flow cytometry after a 4-hour incubation of ILC/NK-enriched PBMCs from HDs (n = 16) or AML patients at diagnosis (n = 4-13) with medium, the K562 tumor cell line, or blasts at a ratio of 1:1. Representative density plot of CD107a expression is shown in panel C, and the summary results are shown in panel D (1 dot = 1 donor). (E) Representative density plot of HLA-E expression in primary leukemic AML blasts. (F) Summary of HLA-E expression in primary leukemic AML blasts (n = 5). (G) Flow cytometry analysis of CD94, NKG2A, and NKG2C in CD56⁺ ILC1-like cells from AML patients at diagnosis (n = 3-10) and HDs (n = 5-17). One dot = 1 donor. Statistical tests used: panels A-B,D,G: Mann-Whitney U test. **P < .01, ***P < .001, ****P < .0001.