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.