Characterization of human T cell clones isolated from immortalized T cell lines generated by oncogene transfection

Previously me established a method to reproducibly immortalize human T cells by oncogene transfection (2), Based on our findings which showed that these immortalized T cells demonstrated cytotoxicity against K562 cells in a MHC-nonrestricted manner, we attempted to obtain T cell clones which exhibit natural killer like activity. In this study, we tried to isolate immortalized T cell clones by two methods, i) direct limiting dilution, and ii) limiting dilution after stimulation with K562 cells. We succeeded in obtaining 35 T cell clones. Two clones among the 35 were CD4(+), but the rest of the clones were shown to contain a small population of CD8(+) cells together with highly dominating CD4(+) cells, suggesting that CD4(+) T cells were preferantially expanded from T cell lines immortalized by oncogene transfection. However, we can not yet assign the reason why this small population of CD8(+) T cells was retained in the 33 established T cell clones. Eleven out of 19 T cell clones established by method (i) and 11 out of 16 T cell clones established by method (ii) were shown to be cytotoxic against K562 cells, indicating that these T cell clones still retain their functional properties irrespective of their cloning methods.