Molecular characteristics of the formation of TLSs. Tumor cells continuously release antigen and inflammatory factors to stimulate lymphocytes and stromal cells to secrete CXCL13 and IL-7 and recruit lymphoid tissue-inducing cells (LTis). The formed LTis promote lymphocyte infiltration by HEVs through the expression of TLα1β2 and binding to receptors on stromal cells or lymphoid tissue organizer cells (LTOs), eventually forming TLSs.