Fig. 6 |. Immunotherapy-boosted tumor-infiltrating lymphocytes synthesize saturated PI.

a–c, Sex-matched C57BL/6 mice were injected in the right flank with 1 × 10⁶ B16-F10-OVA cells. After three d, mice were given intraperitoneal injections of anti-PD-1 and anti-CTLA4 (aPD1 + aCTLA4) or matching isotype controls (IgG1 + IgG2) every three d for three rounds in total. Tumor growth was measured up to day 16 after tumor injection and CD8⁺ T cells were isolated on day 12 after tumor injection to measure T cell function and lipid composition. b, Average tumor diameter at indicated time points. n = 14 biologically independent animals; two-way ANOVA corrected for multiple comparisons (Sidak test) comparing the two groups at each time point across the dataset. c, Lipids were analyzed from TILs on day 12 after tumor injection. Saturation of acyl chains is expressed as a percentage of total PI. Statistical analysis was carried out on the summed percentage of saturated PI on n = 7 IgG1 + IgG2 and n = 8 aPD1 + aCTLA4 biologically independent samples using an unpaired two-tailed t-test. d–h, CD8⁺ T cells were isolated from the blood of adult participants with histologically confirmed stage III or IV malignant melanoma (n = 13) on the day of immune checkpoint inhibitor treatment initiation (before therapy, “pre”) and then when the participant presented for the second administration of treatment (after therapy, “post”). Long-term disease response (non-responder versus responder) to checkpoint inhibitor treatment was assessed (median follow-up time of 318 d). Lipids were extracted and analyzed by LC–QqQ–MS/MS. e,f, Lipids were analyzed before and after therapy. Saturation of acyl chains is expressed as a percentage of total PI. Statistical analysis was carried out on the summed percentage of saturated PI using a two-tailed Wilcoxon matched-pairs signed-rank test (n = 13). g,h, Lipids were analyzed and grouped by response to therapy. Relative intensity of saturated PI species normalized to pre-therapy level is shown. Statistical analysis was carried out using a two-tailed Wilcoxon matched-pairs signed-rank test (n = 6 responders and n = 6 non-responders). Error bars show the s.e.m. s.c., subcutaneous.