The link between T cell activation and development of functionally useful tumour-associated high endothelial venules.

High endothelial venules (HEVs) are specialized postcapillary venules that specifically serve to recruit circulating lymphocytes to secondary lymphoid organs (SLOs) where cognate antigens can be encountered, and immune responses can be initiated. The presence of HEV-like vessels in primary human solid tumours and their association with lymphocyte infiltration and favourable clinical outcomes and response to immunotherapy have provided a rationale for therapeutically inducing these vessels in tumours for immunotherapeutic benefit. Here we specifically discuss evidence for a link between T-cell activation and development of useful tumour-associated HEV (TA-HEV). We discuss the molecular and functional features of TA-HEV, highlighting the benefits for promoting tumour immunity and the important unanswered questions that need to be addressed before TA-HEV induction can be optimized for immunotherapeutic benefit.