Figure 1.

Role of vascular microenvironment in regulation of tumor immunity – Vascular microenvironment regulates T cell-based tumor immunity via multifactorial mechanisms: structurally and topologically abnormal vasculature hampers T cell infiltration; downregulated expression of adhesion molecules, such as ICAM-1 and VCAM-1 in tumor-associated endothelial cells (ECs), impedes T cell adhesion to and diapedesis through the tumor vessel wall; tumor ECs produce multiple cytokines that induce immunosuppressive phenotypes in macrophages and inhibit T cell survival and activation; the vascular microenvironment generates locoregional stresses including hypoxia, nutrient deprivation, and excessive immunosuppressive metabolites and enzyme, reducing T cell activity and inducing T cell exhaustion.