An investigation into the role of tumour cell loading on dendritic cell maturation

Introduction: Dendritic cells (DCs) have been extensively utilised in cancer immunotherapy due to their central role in immunity. Despite evident CTL reactivity, vaccination with peptide-pulsed DCs rarely achieved clinical benefits. Apoptotic tumour cells (TCs) are promising candidates for DC loading, however the induction of apoptosis in an immunogenic context is a pre-requisite to achieve immunity rather than tolerance. The aim of this study is to induce an immunogenic cell death in TCs using the synthetic analogue of dsRNA, poly(I:C), to facilitate presentation of antigenic peptides by DCs thereby inducing Th 1 cell and CTL differentiation. Methods: A variety of TC lines were tested for their sensitivity to apoptosis in response to poly(I:C), and IFN-γ was used to sensitise for dsRNA induced cell death. The ability of human monocyte-derived DCs to endocytose such tumour preparations was assessed by flow cytometry. DC maturation and activation was measured by cytokine detection and cell surface phenotyping. The ability of DCs to drive a Thl biased response was determined by cytokine assays and intracellular cytokine staining. The expansion of antigen specific CTLs was investigated by pre-loading of DCs with the well characterised influenza peptide, M 1. Results: Results show that poly(I:C) pulsing can result in apoptosis of some tumour lines which is augmented by IFN-γ (IFN-γ/poly(I:C) pulsing), while ensuring cytosolic delivery of poly(I:C) by a transfection reagent (IFN-γ/poly(I:C) transfection) renders causes apoptosis in all tumour lines. Endocytosis of IFN-γ/poly(I:C) TCs can mature and activate DCs to induce the development of a Th 1 biased response regardless of whether TC apoptosis is induced by pulsing or transfection with poly(I:C). Conclusion: Taken together, the data suggest that poly(I:C) induced tumour cell death may provide DCs with appropriate 'danger signals' which in turn can drive the development of a Thl biased response required for the development of anti-tumour immunity.EThOS - Electronic Theses Online ServiceGBUnited Kingdo