Figure 1.

Intrametastatic immune landscape. (a) an in situ lymphocytic infiltration is mediated through chemokines and attraction inside or around the tumor microenvironment. IL15, produced mainly by activated myeloid cells and tumor cells, activates cytotoxic CD8 T-cells and NK-cells, which together with Th1 cells produce IFNG, a major cytokine involved together with XCL1 in shaping a good immune contexture and in activating cDC1 cells. These activated cDC1 cells, by producing chemokines such as CXCL9/10 are attracting CXCR3+ cells, notably memory CD45RO+ T-cells, cytotoxic CD8 T-cells and NK-cells. (b) In parallel, IL15 is also inducing a direct in situ lymphocytic proliferation, which expand the local pool of intratumoral cytotoxic CD8 T-cells. IL15 and these proliferating CD8 T-cells were associated with prolonged survival in cancer patients