Figure 4.

TGF-β-mediated immune suppression in CAR-NK cells

Exogenous TGF-β decreases the cytolytic activity of B7H3 CAR-NK cells by downregulating NK cells' endogenous receptors. (A) Percentage of U87 MG lysis by TGF-β-treated (dashed lines) and untreated or control (solid lines) by UT-NK (black line) and B7H3 CAR-NK cells (red line). Representative experiment example out of n = 3 lines generated. (B) The mean specific U87 MG cells lysis at 20:1 E:T ratio. Red bar represents the NK cell’s target lysis in presence of TGF-β and the black bar represents the NK cell’s lysis in absence of TGF-β. The individual point represents the individual donor and error bars represent the standard deviation. (C and D) Representative surface expression NKG2D (C) and of CD16 (D) on UT-NK and B7H3 CAR-NK cells after culture in the presence (red histogram) or absence (blue histogram) of TGF-β (5 ng/mL). (E and F) Mean MFI of CD16 (F), NKG2D (E) for UT-NK and B7H3 CAR-NK cells after culture in the presence or absence of TGF-β (5 ng/mL) (n = 4). Red bar represents the NK cell’s mean MFI in presence of TGF-β and the Black bar represents the NK cell’s mean MFI in absence of TGF-β. The individual point represents the individual donor and error bars represent the standard deviation. (∗p < 0.05, all comparisons). (B) The p values were generated by the Holm-Sidak multiple comparison test after two-way analysis of variance. (E and F) The p values were generated by the Mann-Whitney test.