Figure 6. Proposed cellular processes impacted by CD8α:MyD88-expressing T cell in the tumor microenvironment.

A) We observed an increased frequency of CD8α:MyD88 T cells in the tumor, indicating enhanced infiltration, expansion, and/or survival of CD8α:MyD88–transduced T cells. B) CD8α:MyD88 T cells exhibit enhanced proliferation in response to tumor antigen and tumor cells in culture; an effect that we speculate might be occurring in vivo. C) CD8α:MyD88 T cells produce increased levels of IFN-γ. D) Increased levels of the IFN-γ can lead to induction of the T cell chemokine CXCL9 which were detected in the tumor and could contribute to the enhanced CD8⁺ T cell numbers observed in the tumor. E) IFN-γ has the ability to influence the antigen presentation machinery and is reflected by an enhanced expression of MHC I on non-hematopoietic (CD45⁻) cells, presumably tumor cells, and F) increased MHC II and CD86 expression on DCs. G) There were decreased levels of CCL2 in the tumor, which is a monocyte chemoattractant protein. Monocytes are the precursors of macrophages, and accordingly, an overall decreased number of macrophages were detected in the tumor of CD8α:MyD88 T cell-treated mice. H) The macrophages that were present were skewed from a pro-tumorigenic phenotype towards a phenotype favoring anti-tumor immunity.