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.
Keywords: Chemokines, cytokines, immunotherapy, intratumoral, microenvironment, scaffolds, T lymphocytes.
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