BACKGROUND: Mutations in the PRF1 gene account for up to 58% of familial haemophagocytic lymphohistiocytosis (FHL) syndromes. The resulting defects in effector cell cytotoxicity lead to hypercytokinaemia and hyperactivation with inflammation in various organs. OBJECTIVE: To determine whether autologous gene corrected T cells can restore cytotoxic function, reduce disease activity and prevent haemophagocytic lymphohistiocytosis (HLH) symptoms in in vivo models. METHODS: We developed a gammaretroviral vector to transduce murine CD8-T cells in the prf-/- mouse model. To verify functional correction of prf-/- CD8-T cells in vivo, we used a lymphocytic choriomeningitis virus (LCMV) epitope transfected murine lung carcinoma cell tumour model. Further, we challenged gene corrected and uncorrected mice with LCMV. One patient sample was transduced with a PRF1 encoding lentiviral vector to study restoration of cytotoxicity in human cells. RESULTS: We demonstrated efficient engraftment and functional reconstitution of cytotoxicity after intravenous administration of gene corrected prf-/- CD8-T cells into prf-/- mice. In the tumour model, infusion of prf-/- gene corrected CD8-T cells eliminated the tumour as efficiently as the transplant of wild type CD8-T cells. Similarly, mice reconstituted with gene corrected prf-/- CD8-T cells, displayed complete protection from the HLH phenotype after infection with LCMV. Patient cells showed correction of cytotoxicity in human CD8-T cells after transduction. CONCLUSION: These data demonstrate the potential application of T cell gene therapy in reconstituting cytotoxic function and protection against HLH in perforin deficiency
