Gene transfer to primary acute myeloid leukaemia blasts and myeloid leukaemia cell lines

The transfer of genes encoding co-stimulatory molecules and/or cytokines to leukaemia cells in order to create autologous tumour vaccines represents a potential immunotherapeutic strategy for treating acute myeloid leukaemia (AML). One of the essential requirements for this strategy if it is to be a pplicable in a clinical setting is a high efficiency of gene transfer to pr imary human AML blasts. Using green fluorescent protein (GFP) as a reporter gene, we have systematically evaluated a variety of physical, chemical and viral vector-based gene transfection systems in order to determine which g ave the highest gene transfer efficiency to myeloid leukaemia cell lines an d primary AML blasts. Transfection efficiency was low for all the physical and chemical transfection methods tested. Retroviral vector-based infection gave a high efficiency of gene transduction in two of the four leukaemia c ell lines (KG1a and U937), but was low in primary AML blasts. An adenoviral vector gave a high transduction efficiency in all of the leukaemia cell li nes with the exception of the HL60. In primary AML blasts, derived from 19 patients, gene transduction efficiency was variable, ranging from 1.1% to 6 7.1% (mean 12.1%). Following culture in cytokines GM-CSF/IL-4/CD40L, which induced differentiation of AML blasts to dendritic-like cells, transduction efficiency was increased between two- and eightfold in 6 out of the 15 cas es that underwent differentiation.