Abstract Infiltration of lymphocytes into solid tumors represents a significant bottleneck to successful control of tumor growth. The nature of tumor blood vessels is an important factor governing both quantitative and qualitative features of the immune infiltrate. In this issue, Sawada and colleagues identify a genetic signature for blood vessels, most notably high endothelial venules, which are associated with tertiary lymphoid structures and improved clinical outcome. See related article by Sawada et al., p. 468 (4).