Radiotherapy/Chemotherapy-Immunotherapy for Cancer Management: From Mechanisms to Clinical Implications

Figure 2

Mechanism of vaccines plus radiotherapy. CD8 T cells can recognize the tumor antigen peptide–MHCI molecule complex on the surface of tumor cells and then proliferate and differentiate into cytotoxic T lymphocytes (CTL) with a specific killing activity following activation, which mediates the necrosis or apoptosis of tumors. Exfoliating from the surface of tumor cells, tumor antigens are absorbed and processed by antigen-presenting cells (APC) as polypeptide molecules and then expressed on the surface of APC in the form of a tumor antigen peptide–MHCII molecule complex. Tumor antigen-specific CD4 T cells recognize and activate the complex, release cytokines such as interleukin-2 (IL-2) and γ-interferon (IFN-γ) to activate monocytes-macrophages and NK cells, and enhance the killing function of CD8 CTL. IFN, tumor necrosis factor (TNF), and CD4 CTL can directly kill tumor cells. The combination of vaccines and radiotherapy may produce a synergistic effect, which can enhance vaccine-mediated tumor cell lysis while upregulating MHC, Fas, intercellular cell adhesion molecule-1 (ICAM-1), and TAA [30, 31].