Tumors actively recruit and expand Tregs through multiple mechanisms: CCL22 secretion, TGF-² production, and metabolic competition. High Treg infiltration correlates with poor prognosis in most solid tumors (with some exceptions like colorectal cancerLoading...).
Tregs suppress anti-tumor immunity through CTLA-4-mediated inhibition of dendritic cellsLoading..., IL-2 consumption (starving effector T cells), and secretion of inhibitory cytokines (IL-10, TGF-²).