HIGH-LEVEL EXPRESSION FROM A CYTOMEGALOVIRUS PROMOTER IN MACROPHAGE CELLS

To identify vectors that provide optimal gene expression in human hema topoietic cells, we investigated retroviruses containing the adenosine deaminase (ADA) gene under the transcriptional control of the promote rs/enhancers of Moloney murine leukemia virus and the human cytomegalo virus (CMV) immediate-early gene, ADA expression was monitored in tran sduced human multipotential promyelocytic leukemic HL-60 cells and hum an monocytic leukemic THP-1 cells, HL-60 cells can be induced by phorb ol ester to differentiate into macrophage lineage cells and by retinoi c acid into granulocytic cells, THP-1 cells undergo phorbol ester-indu ced differentiation to macrophage cells, In LNCA-transduced HL-60 deri ved macrophage cells, ADA controlled by the CMV promoter was expressed at 100.0 mu mol/hr . mg, in contrast to 1.2 mu mol/hr . mg from LN-tr ansduced control cells, LNCA-transduced THP-1 macrophage cells showed a similar increase in ADA activity over control cells, These elevated enzyme activities were confirmed by Northern blots, which showed subst antial increases in ADA mRNA derived from the CMV promoter, This sugge sts use of the CMV promoter for gene therapy targeted at macrophages, as, for example, in the treatment of lysosomal storage disorders such as Gaucher disease, These inducible cell lines have allowed the evalua tion of transduced gene expression in proliferating and differentiatin g hematopoietic cells that may serve as an in vitro model of bone marr ow-targeted gene therapy.