The differentiation and anti-tumor immunity of memory T cells after specific TCR gene transfection and tumor antigen induction

Objective To investigate the differentiation of memory T cells after the activation of TCR gene transfected T cells by tumor antigen stimulation in vitro, and to determine the phenotype and anti-tumor immunity of the induced memory T cells. Methods PBMC were isolated by density gradient centrifugation. T cells were infected by recombinant TCR adenovirus and the expression efficiency of transgene in T cells was detected by FACS. T cells were stimulated by 9-amino long HLA-A2+ epitope from AFP218-226. Expression of molecular markers of memory T cell on TCR gene transfected T cells after activation was detected by FACS. Specific lysis of T cells was evaluated by MTT assay. The ratio of apoptotic cells in the target cells was detected by Annexin V/PI double-labeled FACS. The secretion of cytokine IFN-γ and IL-2 of T cells was quantified by ELISA assay. Results The ratio of exogenous TCR positive cells was about 30% of T cells 3 days after infection. Tumor-specific TCR gene modification redirected the antigen specificity of T cells effectively. TCR gene transfected T cells were activated effectively by stimulation of AFP. The ratio of CD45RO+cells was increased after activation and reached about 50% of T cells 14 days after stimulation. Most of CD45RO+cells were CD62L–CD44–. The ratio of CD62L positive cells was then increased. Cell clusters with CD62L+CD44+TCM phenotype appeared in effector T cells eventually. Tumor specific TCR gene modification enhanced the abilities of T cells to lyse HLA-A2+AFP+target cells, to induce HepG-2 apoptosis, and to secret IFN-γ. Stimulation of TCR gene transfected T cells by tumor antigen effectively enhanced the anti-tumor activity of T cells. Conclusion Tumor specific TCR gene modification redirected antigen specificity of T cells effectively. Antigen specific T cells stimulated by tumor antigen initiate the differentiation of memory T cells, which enable effector T cells to acquire the phenotypic characters of TCM and mediate enhanced response upon re-exposure to tumor antigen.