The most sought-after outcome for treatment of autoimmune diseases is reinstatement of immune regulation or tolerance through antigen-specific immunotherapy. Autoimmune diseases, including type 1 diabetes (T1D), often result from CD8+ T cell- mediated destruction. Transfer of engineered haematopoietic stem cells (HSC) has been shown to induce antigen specific immune tolerance in mouse models. Whether gene-engineered HSC can be exploited for modulation of human T cell responses remains undetermined. To gain insight we aimed to express an antigen of interest in humanised mice through engineering of HSC. HSC were engineered with lentivectors (LV) coding for preproinsulin (PPI), a principal T1D associated autoantigen. We generated lentivectors containing PPI under the control of a ubiquitous promoter (EF1α) to target antigen expression to all HSC progeny including antigen-presenting cells (APC). To restrict antigen expression to APC, we generated LV containing PPI under the control of an HLA-DRα promoter. Finally, to restrict PPI expression to conventional dendritic cells (DC), a ‘professional’ APC type, we generated lentivectors containing PPI under the control of a ZBTB46 promoter. Initial studies of antigen expression and specificity of expression were performed in vitro. Then, NSG-SGM3 mice were humanised by transfer of transduced HSC to neonatal mice. In vivo specificity of expression in humanised NSG-SGM3 mice was validated by flow cytometry analysis. PPI specific CD8+ T cells were generated in vitro with LV coding for TCR restricted to PPI1-11 and PPI15-23 prior to testing these LV in humanised mice. Antigen-specific activation of these CD8+ T cells was determined in an antigen presentation assay. We will monitor PPI specific CD8+ T cells in humanised mice to determine the effect of antigen expressing APC or DC on cognate CD8+ T cells. These studies should provide proof of principle that LV-based HSC gene therapy can be used to modulate human CD8+ T cell responses.