Tumors use complex mechanisms to evade and
suppress the immune system
Active T cell
Inactive T cell
Tumor-
associated
antigens
APC
A. Ineffective presentation of
tumor antigens to immune
system
B. Recruitment of
immunosuppressive cells
C. T-cell checkpoint
dysregulation
(eg, PD-1, CTLA-4)
Immunosuppressive
factors
D. Tumor release of
immunosuppressive factors
(eg, TGF-β, IDO, IL-10)
Treg
4
CTLA-4=cytotoxic T-lymphocyte-associated protein 4;
IDO= indoleamine 2,3-dioxygenase; IL=interleukin; MDSC=myeloid-derived
suppressor cell; MHC=major histocompatibility complex;
TGF-β=transforming growth factor beta.
Vesely MD et al.
Ann Rev Immunol
. 2011;29:235–271.
Tumor cells
