CCL2 and lung cancer: To evade immune surveillance, lung cancer cells employ multilayered strategies (Figure 2): they directly secrete immunosuppressive factors (e.g., TGF-β and IL-10) to impair CD8+ T and NK cell activity and regulate the quantity and function of Treg cells; lung cancer cells release signals (e.g., CCL2) to recruit immunosuppressive cells (e.g., CCR2+ tumor-associated macrophages[TAMs], MDSCs, and Th2) to create an immunosuppression microenvironment that contributes to tumor progression (Ni et al., 2023; Bergerud et al., 2024); and critically, exploit immune checkpoint pathways.