Figure 7. IL-6 within senescent microenvironments mediates immunosuppression and tumour promotion.

(a) Flow cytometry for G-MDSC following IL-6 depletion in non-senescent (Non-Sen) or senescent (Sen) isografts. *P value <0.05, Student's t-test. ns is non-significant. Data are mean % of CD45⁺ population+s.e.m. n=3–7. (b) Flow cytotmetry of bone marrow cells treated with CM depleted of IL-6. Set-up shown in Fig. 3j. *P value <0.05, Student's t-test. ns is not significant. Data are mean # of cells per plate+s.e.m. n=4. (c) T-cell suppression assay following IL-6 depletion. Set-up shown in Fig. 4d. Bone marrow cells were conditioned with Sen+IgG (Sen), Sen+αIL6 or control (CTR) medium. *P value <0.05, by analysis of variance. Data are mean % proliferation+s.d. of triplicates. n=3. (d) Imaging following IL-6 depletion in PDSC5 tumour co-injections. Non-Sen with PDSC5 (Non-Sen), Sen+IgG with PDSC5 (Sen) and Sen+αIL6 with PDSC5 on day 9 post injection. (e) PDSC5 tumour growth in IL-6 depleted Non-Sen and Sen isografts. Data are represented as MPF (photons per second)+s.e.m. *P-value<0.05, Student's t-test. ns is not significant. n=10. (f) MK16-Ras tumour growth in IL-6-depleted Non-Sen and Sen isografts. *P value <0.05, Student's t-test. ns is not significant. Data are mean tumour area (mm²)+s.e.m. n=7–22. (g) Depletion of IL-6 has no direct effect on PDSC5 tumour growth when stromal cells are not present. Data are MPF+s.e.m. ns is not significant, P⩾0.05, Student's t-test. n=8–10. (h) Depletion of IL-6 has no direct effect on MK16-Ras tumour growth when stromal cells are not present. Data are mean tumour area (mm²)+s.e.m. ns is not significant, P⩾0.05, Student's t-test. n=13–15. (i) IL-6 neutralization does not impact in vitro tumour cell growth. Sen CM depleted of IL-6 or treated with IgG do not differentially impact PDSC5 or MK16-Ras growth. Data are mean fold growth+s.e.m. ns is not significant, Student's t-test. n=6. MPF, mean photon flux.