 Immunology Tumor angiogenesis can impact immune response in renal cell carcinoma patients. A naturally occurring CD4 T cell subset, regulatory CD4CD25 T cells, has emerged as the dominant T cell population governing peripheral self- tolerance by inhibiting effector T cell. The ability of anti-angiogenic therapy to block VEGF may allow better maturation of dendritic cells and a reduction of the number of regulatory CD4CD25T cells. 