Lymphocytes

The manipulation of gene expression in primary lymphocytes has been shown to have potential therapeutic applications for immunodeficiencies (1 –3 ), and cancer immunotherapy (4 ,5 ). Efficient gene transfer is an absolute prerequisite for developing successful clinical gene therapy protocols. At present, viral gene transfer vectors based on murine leukemia virus (MLV) are used in most clinical trials and have been used successfully to transduce cells from various tissues, including cells of hematopoietic origin (6 –8 ). However, transduction of primary lymphocytes has been limited primarily by the requirement that the cells be proliferating for stable retroviral integration (9 ). Although potent induction of cell proliferation in vitro has been used to overcome this problem (1 ,10 –12 ), it has now become evident that activation stimuli such as antibodies and mitogens result in alteration of the CD4/CD8 ratios and T-cell receptor (TCR) repertoire composition of T lymphocytes and induce changes of their cytokine secretion profile, thus precluding preservation of the pool of na�ve lymphocytes and their functional integrity (13 ,14 ).