HEMATOLOGICAL RECONSTITUTION AND GENE-THERAPY - RETROVIRAL TRANSFER OF THE BACTERIAL BETA-GALACTOSIDASE ACTIVITY INTO HUMAN HEMATOPOIETIC CD34(-POPULATIONS AND INTO T-LYMPHOCYTES DERIVED FROM THE PERIPHERAL-BLOOD() CELL)

We report the possibility to transfer marker genes coding for beta-gal actosidase activity using retroviral vectors into human peripheral bro od CD34+ cells, peripheral blood T-lymphocytes and into the growth fac tor-dependent human hematopoietic cell line TF-1. Using the MFG-nlsLac Z and the FLac vector and various packaging ce!ll lines, we demonstrat ed retroviral transfer and high expression of a bacterial beta-galacto sidase activity induced by the nlsLacZ gene or the Sh-ble/LacZ gene. K inetics of expression of the transgenes were analyzed both in primary cells and cell lines. Absence of cytotoxicity related to the expressio n of the bacterial beta-galactosidase was assessed in both cell types. These results open interesting prospectives for the use of the beta-g alactosidase activity to mark and follow the fate of genetically modif ied cells isolated from patients prior to reimplantation.