Fig. 4: Neutrophil-mediated tumor cell killing is achieved via ferroptosis.

a Viability (luminescence; A.U, arbitrary units) of LN229^TAZ(4SA) cells cultured alone or with differentiated 32Dcl3 cells treated with various cell death inhibitors (n = 2). b Viability (luminescence) of LN229^TAZ(4SA) cells cultured alone, with differentiated 32Dcl3, with differentiated HL-60 cells, or with TANs treated with 2 µM ferrostatin-1, 0.1 (w/32D) or 0.2 (w/HL-60 or TANs) mM deferoxamine (DFO), or DMSO. Percent survival is normalized to LN229^TAZ(4SA) tumor cells cultured alone and treated with the same compound (n = 3). Unpaired two-tailed t-test. c Representative flow cytometry analysis of BODIPY in LN229^TAZ(4SA) cells cultured alone, with TANs, or with differentiated 32Dcl3 cells (n = 3). d Fold change in median fluorescence intensity (MFI) of flow cytometry analysis in c (n = 3). Ordinary one-way ANOVA. e Low- and high-magnification transmission electron microscopy (TEM) images of LN229^TAZ(4SA) tumor cells cultured alone, with differentiated 32Dcl3, or with differentiated HL-60 cells. Five image fields were examined for each condition from two independent experiments with consistent observations. f Representative image of in situ Liperfluo dye-loaded brain slice from a LN229^TAZ(4SA) tumor-bearing mouse. g Representative high-magnification images of the rectangular area outlined in red in f showing Liperfluo and DAPI signals. h Fold change in MFI of flow cytometry analysis in Supplementary Fig. 4j. CD45^– tumor and CD45⁺ immune cells were isolated from LN229^TAZ(4SA) tumor-bearing mice (n = 7). Each pair represents cells isolated from the same animal. Paired two-tailed t-test. i Chromogenic immunodetection of PTGS2 in a LN229^TAZ(4SA) tumor section. The outlined area is enlarged and shown on the right. j Representative low- and high-magnification TEM images from LN229^TAZ(4SA) tumor-bearing mice brain sections at early tumor progression (left; 16 days after implantation) and upon reaching endpoints (right; 30 days after implantation). For f, g, i, and j, three animals were examined independently with similar observations. a–j n indicates number of animals or biologically independent samples (with each sample from an independent experiment). Numerical data are presented as mean ± s.e.m. All scale bars are in μm. Source data are provided as a Source Data file.