Figure 1

Diagram for the expression of immunoregulatory molecules during the transformation of epithelial cells to carcinoma tumor cells under the pressure from immune surveillance. Loss of classical and/or up-regulation of non-classical HLA class I expressions may be able to avoid the stimulation of cytotoxic CD8⁺ T cells and NK cells; Up-regulation of pro-apoptotic ligands, such as Fas L and RCAS1 may directly induce anti-carcinoma immune cell death. Secretion of TGF-beta1 and Gal-1, expression of immune inhibitor ligands (B7-H1 -H3 and -H4), up-regulation of IDO and/or ARG activity and/or expansion of cellular immunosuppression by MDSCs and Foxp3 Treg cells could generate an immunosuppressive microenvironment, protecting carcinoma cells from immune surveillance.