Marked anti-tumor effects of CD8+CD62L+ T cells from melanoma-bearing mice

Abstract

CD8+CD62L+ T cells have been shown to play pivotal roles in anti-viral immunity, chronic myeloid leukemia and renal cell carcinoma. Recently, CD8+CD62L+ T cells from naïve mice (nCD8+CD62L+ T cells) have shown superior anti-tumor properties in melanoma-bearing mice. Considering that antigen-specific memory T cells have shown to possess more potent immunity than non-specific memory T cells, we hypothesized that CD8+CD62L+ T cells from tumor-bearing individuals (mCD8+CD62L+ T cells) might have superior anti-tumor effect than nCD8+CD62L+ T cells. Therefore, we investigated phenotypes, functions and the in vivo distribution of mCD8+CD62L+ T cells in tumor-bearing mice. We found that, while keeping the features of central memory T cells, the frequency of mCD8+CD62L+ T cell in the spleen of tumor-bearing mice was significantly higher than that the one of nCD8+CD62L+ T cell in naive mice. Moreover, we demonstrated that mCD8+CD62L+ T cells had higher proliferation rate and IFN-γ production than nCD8+CD62L+ T cells, in vitro. We performed adoptive transfer of mCD8+CD62L+ T cells into melanoma-bearing mice and tracked them in spleen, lymph nodes and in melanoma tissues. Our results show that mCD8+CD62L+ T cells had stronger in vivo anti-tumoral activity than nCD8+CD62L+ T cells. This study highlights the therapeutic potential of mCD8+CD62L+ T cells in the immunotherapy of melanoma and possibly other tumors.