TNFSF4 and head and neck squamous cell carcinoma: In HNSCC patients with early stage I/II disease, CD3(+) sEV carried high levels of immunostimulatory cargo (i.e., had high expression of OX40 or OX40L), while in patients with advanced disease and positive lymph nodes, CD3(+) sEV had low levels of OX40 or OX40L, and in coincubation assays induced apoptosis of CD8+ effector T cells and promoted expansion of Treg [19].