TUMOR IMMUNITY

TUMOR IMMUNITY

IMMUNE SURVEILLANCE
Function of the immune system is toconstantly “scan” the body for emerging malignant cells and destroy them

If tumors grow in immunocompetent individuals, the reasons include
1. Tumor cells are invisible to host immune system
2. Tumor cells activate mechanism that suppress host immunity – TUMORS EVADE HOST IMMUNITY!- one of the important hallmarks of cancer.

TUMOR ANTIGENS- Protein molecules expressed on tumor cell. They can be
a. New antigens
b. Overexpression/aberrant expression of normal proteins
c. Antigens produced by oncogenic viruses

ANTITUMOR EFFECTOR MECHANISMS
Killing of tumor cells by Cytotoxic T Lymphocytes which are specific for tumor antigens – major mechanism

Other mechanisms
Antitumor CD4+ T-cell responses
Natural killer (NK) cells
Activated macrophages

MECHANISM OF IMMUNE EVASION BY CANCER CELLS
1. Selective outgrowth of antigen negative variants
2. Loss or reduced expression of MHC molecules
3. by upregulating negative regulatory “checkpoints”
4. Secretion of immunosuppressive factors
5. Induction of regulatory T cells (Tregs)

Applications
Treatment with specific checkpoint inhibitor antibodies
Tumor neoantigen burden is a good predictor of response- they are most likely
to respond to checkpoint blockade therapy.

For detailed explanation and tutorial watch here