| Abstract: | We have succeeded in establishing a method to reproducibly immortalize human T cells by oncogene(s) transfection (Alam, 1997).
This study was based on our previous discoveries that these immortalized T cell lines contained T cells which showed cytotoxicity
against K562 cells in MHC-nonrestricted manner. Then we attempted to obtain human T cell clones exhibiting natural killer-like
activity. Here, we tried to establish clones from these immortalized T cell lines by limiting dilution after stimulation with
K562 cells, and then obtained 16 T cell clones. Two clones among them maintained their stability and showed vigorous growth
phenotype. Thus we selected these two clones for further analysis. One is derived from the T cell line transfected with oncogenes
ras and fos, the other is from the T cell line transfected with myc and fos. Both clones were demonstrated to be CD4+ T cells, indicating that CD4+ T cells were preferably expanded from T cell lines immortalized by oncogene transfection. These two clones showed cytotoxicity
against K562 cells, indicating that these two T cell clones still retain a natural killer-like activity of killing target
cells of K562 cells in a MHC-nonrestricted manner. The natural killer-like activity of the T cell clones was shown to be stable
for more than 2 yr when cultured in the presence of IL-2, indicating that introduction of two oncogenes such as ras/fos or
myc/fos resulted in the acquisition of infinite replicative life-span but not in transformational alteration of cellular function.
This revised version was published online in August 2006 with corrections to the Cover Date. |
