Fig. 3: CD8⁺ T cells inhibit metastasis.

a Representative CyTOF tSNE plots of 67NR and 4T1 tumours grown in wild-type BALB/c mice mammary fat pad. b Quantification of CyTOF data of immune populations within CD45⁺ cells from 67NR (orange) and 4T1 (cyan) tumours (n = 3). In mice with no CD8⁺ T cells (BALB/c CD8KO), non-metastatic 67NR breast cancer cells metastasise to the lung from the mammary fat pad (c–j). c A cartoon showing the mammary fat pad injection (top). Representative images of whole-body bioluminescence of BALB/c wild-type and BALB/c CD8KO mice harbouring 67NR tumour (middle) and of tumours excised from these mice (bottom) (n = 5). d The mean tumour volume of the tumours excised from these mice (n = 5). e Representative H&E staining of tumours from BALB/c wild-type and BALB/c CD8KO mice (n = 5). Scale bar: 200 µm. f Representative bioluminescence images of lungs excised from BALB/c wild-type and BALB/c CD8KO mice harbouring 67NR at the orthotopic mammary fat pad (top). g The mean total flux from these lungs (bottom) (n = 5). h The number of visible lung nodules in BALB/c wild-type and BALB/c CD8KO tumour-bearing mice (n = 5). i H&E staining of representative lungs from BALB/c wild-type and BALB/c CD8KO mice. Scale bar: 200 µm. j The number of CTCs isolated from BALB/c wild-type and BALB/c CD8KO mice harbouring 67NR tumours at the mammary fat pad (n = 5). Quantitative data are mean ± SEM. Statistical analyses were performed by unpaired two-tailed Student’s t test for panels d, h and j or by F test for panels b and g; ns indicates not significant, ^∗P ≤ 0.05, ^∗∗P ≤ 0.01, ^∗∗∗∗P ≤ 0.0001.