Initiation of Tertiary Lymphoid Structures for Cancer Immunotherapy

Tertiary lymphoid structures (TLSs) are ectopic lymphoid aggregates formed by lymphocytes and antigen-presenting cells within chronic inflammatory microenvironments or tumor microenvironments (TMEs), and their initiation phase is a critical step for mounting an effective antitumor immune response. TLS initiation depends on the interplay between lymphoid tissue inducer cells and lymphoid tissue organizer cells and is finely regulated by multiple cytokines and chemokines. This review systematically summarizes the key triggers and signaling networks driving TLS initiation, elucidating how TLSs reshape the TMEs, facilitate antigen presentation, and recruit immune cells to enhance antitumor immune responses. Furthermore, potential strategies to modulate TLS initiation are discussed, along with the emerging role of TLSs as promising targets in cancer immunotherapy.