GENETIC-MODIFICATION OF HUMAN PERIPHERAL-BLOOD LYMPHOCYTES WITH A TRANSDOMINANT NEGATIVE FORM OF REV - SAFETY AND TOXICITY

A transdominant mutant form of the rev gene, M10, confers resistance t o infection by the human immunodeficiency virus (HIV) in vitro and is currently under investigation as a potential intervention in acquired immunodeficiency syndrome (AIDS). In this report, we examine three iss ues relevant to the safety of autologous transfer of human T cells gen etically modified with Rev M10. First, the potential for malignant tra nsformation was assessed in vitro using interleukin-2 (IL-2) dependenc e and fibroblast transformation assays, and tumorigenicity was evaluat ed in severe combined immunodeficient (SCID) mice. Possible toxicity w as evaluated by pathologic analysis following adoptive transfer of gen etically modified human T cells into SCID mice. Second, methods were d eveloped that permit T cell activation required for gene transfer but do not allow replication of endogenous HIV. Third, T cell function was evaluated in peripheral blood lymphocytes (PBL) of HIV-seropositive d onors transduced with Rev M10 and compared to a negative control mutan t, Delta Rev M10. By all criteria, no oncogenicity or toxicity was obs erved. Human T cells transduced with these vectors did not grow in the absence of IL-2 in vitro, and no tumors were observed following trans plantation of genetically modified human cells into recipient SCID mic e. Histopathological analysis of heart, lung, liver, spleen, and kidne y of animals 1-21 weeks following adoptive transfer of gene-modified h uman T cells revealed no significant abnormalities. Additionally, no d ifferences were observed in the pattern of cytokine secretion in enric hed human PBL expressing Rev M10 compared to Delta Rev M10. These resu lts suggest that human T cells genetically modified with Rev M10 or De lta Rev M10 may be administered to patients with minimal toxicity.