Neutralization of IL-10 and TGF beta 1 rescues T cells from tolerogenic mechanisms induced by HER2 vaccine in cancer patients

Purpose/Objective: Dendritic cells (DCs) are the most potent antigen presenting cells in the immune system, which are capable of priming naıve T cells and can stimulate memory T cells and B cells to generate antigen-specific responses. Recent clinical trials were designed to stimulate immune system against HER2+ tumor by using HER2-peptides-based or peptides-loaded-DCs vaccine, but no clinical responses was elicit, probably due to self tolerance mediated by natural and peripheral-induced Tregs. Materials and methods: In our work, CD14+ monocytes were separated from PBMC of healthy subjects or patients with pancreatic and breast cancer overexpressing HER2, to generate dendritic cells (DCs). This DCs were matured and transfected with plasmids coding for extracellular and transmembrane domains of human HER2 then used to activate autologous T cells. Activation of T cells were assessed by intracellular staining, IFNc-ELISpot, ELISA and cytotoxicity assays. Results: Results showed that Human-DCs were able to trigger IFNc release by autologous T cells in healthy donors, but not in cancer patients. Failure of Human-DCs could be ascribe to higher induction of Tregs activity and to higher amount of IL-10 and TGFb1 found in cultures, since neutralization of these two cytokines restored the ability to induce IFNc production. Conclusions: From these we can conclude that cancer vaccine based on self antigen can induce an antitumor response but also activate immune tolerance mechanisms. This finding represent an important point thatbe consider to design cancer vaccines in future