Fig. 4

Overexpression of HO1 in AML cells inhibited NK cell cytotoxicity via targeting the CD48-2B4 axis. A, B HO1 mRNA and protein expression levels in leukemia cell lines. C, D HO1 was overexpressed in THP-1 and silenced in MV4-11 cell lines. E Left graph: percentage survival of Luc‐labeled transduced THP-1 cells after 2 h co-culture with primary NK cells in the presence or absence of CD48 protein, as measured by the bioluminescent imaging system. Right graph: percentage survival of Luc‐labeled transduced MV4-11 cells after 2 h co-culture with primary NK cells in the presence or absence of anti-2B4 antibody, as measured by the bioluminescent imaging system. F Primary NK cells (as effector cells) incubated with transduced AML cells (as target cells) at various effector cell/target cell ratios (E:T = 1:1, 2:1, 4:1, 10:1). NK cell-mediated cytotoxicity as determined by LDH release assay. G CD107a or CD69 expression in NK cells after 6 h co-culture of NK cells with transduced THP-1 cells (1:1 E:T ratio) in the presence or absence of CD48 protein. H Expression of CD107a or CD69 in NK cells after 6 h co-culture of NK cells with transduced MV4-11 cells (1:1 E:T ratio) in the presence or absence of anti-2B4 antibody. *p < 0.05, **p < 0.01, ***p < 0.001 were calculated using Student’s t-test. All experiments were performed in triplicates