Generation of Devil Facial Tumour Cells Co-Expressing MHC With CD80, CD86 or 41BBL to Enhance Tumour Immunogenicity.

The major histocompatibility complex (MHC) molecules play an integral role in the adaptive immune response to transmissible cancers through tumour antigen presentation and recognition of allogeneic MHC molecules. The transmissible devil facial tumours 1 and 2 (DFT1 and DFT2) modulate MHC-I antigen presentation to evade host immune responses and facilitate transmission of tumours cells to new Tasmanian devil (Sarcophilus harrisii) hosts. To enhance T-cell-driven tumour immunogenicity for vaccination and immunotherapy, DFT1 and DFT2 cells were co-transfected with (i) NLRC5 for MHC-I expression or CIITA for MHC-I and MHC-II expression, and (ii) a co-stimulatory molecule, either CD80, CD86 or 41BBL. The co-transfected DFT cells presented enhanced expression of MHC-I and/or MHC-II. As few devil-specific monoclonal antibodies exist, we used recombinant CTLA4 and 41BB fused to a fluorescent protein to confirm expression of cell surface CD80, CD86 and 41BBL. The capacity for these cells to induce T-cell responses including PD1 and IFNG expression was evaluated in in vitro co-culture assays with captive devil peripheral blood mononuclear cells (PBMCs). Although PBMC viability had increased, there was no evidence of enhanced T-cell activation. This system can be used to identify additional factors required to promote activation of naïve devil T-cells in vitro.