CCL21 and IFNγ recruit and activate tumor specific T cells in 3D scaffold model of breast cancer

Effective elicitation of endogenous immunity is associated with improved prognosis for cancer patients. Clinical evidence in hematological and solid cancers shows that intratumoral injection of immunostimulatory genes primes and augments endogenous T cell responses. The ability of pro-inflammatory chemokines/cytokines to facilitate migration/activation of antigen-presenting cells (APC) and lymphocytes prompted our modeling of intratumoral delivery of a chemokine/cytokine combination for breast cancer treatment. Here, we demonstrate that expression of chemokine ligand 21 (CCL21) and interferon gamma (IFNγ) in tumors improves tumor specific T cell recruitment to tumor and activation in the tumor milieu. IFNγ and CCL21 were delivered into tumor cells via plasmids, and transfected cells were seeded to form spheroids on three-dimensional (3D) chitosan-alginate (CA) scaffolds. Co-expression of CCL21 and IFNγ, as evidenced by qRT-PCR and ELISA, induced increased recruitment, binding, and infiltration of anti-neu (p98) peptide specific T cells into the breast tumors as determined by SEM and immunofluorescence assays. The co-expression promoted recruitment of only p98 T cells, but not naïve T cells, demonstrating an antigen-restricted activation. Furthermore, the co-expression impacted T helper (Th) cell immunity, promoting an increase in secretion of pro-inflammatory Th-associated cytokine, tumor necrosis factor alpha (TNFα), and cytotoxic T lymphocyte (CTL)-associated protease, Granzyme B (GzB). Therefore, 3D CA scaffolds may be a useful breast cancer tumor microenvironment model to evaluate T cell function. Further characterization of CCL21-IFNγ mediated anti-tumor immunity will potentially benefit the development of chemokine/cytokine combination platforms as anti-cancer agents.