Induction of human cytotoxic T cell lines directed against point-mutated p21 ras-derived synthetic peptides

The vast majority of mutations in the ras p21 protein are found at position 12, with glycine (G) changing to valine (V), cysteine (C), or aspartic acid (D) constituting most of the mutations. Four human T cell lines from different individuals have been established by in vitro stimulation with 13 mer peptides reflecting the position 12 ras point mutations. All T cell lines were of the CD3+CD4+CD8- phenotype. Specificity of the T cell lines to the stimulating peptide was observed as a proliferative response using the corresponding peptide but not with peptides reflecting other mutations or normal ras (G12). Human T cell lines (specific for V12, C12, or D12 mutations) all respond to corresponding peptides with the production of IFN-γ and IL-6 but not IL-4. Using V12-specific T cell lines, it was demonstrated that Epstein-Barr virus (EBV)-transformed autologous B cell lines could be lysed when incubated with the V12 peptide but not other p21 ras-derived synthetic peptides. Moreover, when the autologous EBV-transformed B cell line was transduced with the p21 ras oncogene containing the V12 mutation in retroviral vector, these cells became susceptible to lysis by the autologous V12 peptide-specific T cell line. These studies indicate that the point-mutated ras gene product may be processed in an appropriate manner to be a target for T cell-mediated cytotoxicity. The point-mutated ras oncogene product may thus potentially serve as a target for T cell-mediated cytotoxicity for a range of human cancers using immunotherapy protocols.