Abstract
Tumor immune responses, including some immunotherapy strategies, can fail because of a number of reasons, such as poor tumor cell immunogenicity or local suppressive cytokine release by dendritic cells (DC) at tumor sites. The retroviral transfer of T-cell receptor (TCR) genes encoding tumor-specific receptors into T cells is a fascinating approach to bypass antigen-presenting cells and allow T cells to directly recognize antigen. It also allows the generation and expansion of potent antitumor cytotoxic T lymphocytes with defined cancer antigen specificities more readily than naive T cells. However, interleukin-10 (IL-10)-exposed dendritic cells (IL-10-DC) have been labeled tolerogenic because of the suppressive effects they have on T cell responses. Whether TCR gene-transduced effector CD8(+) T cells can break through suppressive functions mediated by IL-10-DC is not known. In the current study, we demonstrate the role of IL-10 in modifying the function of DC that otherwise would activate potent TCR gene-transduced T cells against tumor antigens. TCR gene-transduced T cells maintained their cytolytic activity in the presence of DC exposed to low doses of IL-10 during maturation; however, they lost this activity in an antigen-specific manner when exposed to DC matured with high doses of IL-10.