Vaccination and Immunity Theories Quiz

Part 1: Historical Context and Theories

• Ancient Chinese practice involved injecting dry smallpox pustules to induce a mild infection. This is known as variolation.
• Edward Jenner is credited with starting the first vaccination campaigns against smallpox in 1798.
• Louis Pasteur's germ theory proposed that diseases are caused by microscopic organisms.
• William Coley's hypothesis was that inoculating patients with bacteria could shrink tumors.
• Paul Ehrlich proposed the immunosurveillance theory in 1908. This theory suggests the immune system can distinguish tumor cells from normal cells.
• Jenner's vaccination experiments, Ehrlich's antibody research, and the work of Thomas and Burnet with syngeneic mouse models supported the idea that immune cells can distinguish tumor cells from normal cells.
• A major criticism of the immunosurveillance theory was the lack of experimental evidence.
• A true statement about the immune system's role in cancer is that the immune system can both prevent and support tumor growth.

Part 2: Immune System and Cancer

• The adaptive immune response involves T cells and B cells.
• T cells recognize antigens through antigen-MHC complexes.
• If a T cell recognizes a self-antigen in the thymus, it is eliminated.
• Neutrophils and macrophages are primarily responsible for phagocytosis in the innate immune system.
• Regulatory T cells (Tregs) promote a decrease in inflammation.

Part 3: Immunoediting and Tumor Evolution

• The first phase of immunoediting is elimination.
• During the elimination phase, immune cells release IFN-y to kill tumor cells.
• The equilibrium phase of tumor evolution is characterized by a dynamic balance between tumor cells and immune cells.
• The equilibrium phase is closely linked to Darwinian microevolution.
• The escape phase in immunoediting is driven by tumor cells gaining the ability to suppress the immune system. This phase can last for up to 20 years or longer.
• The critical rupture point in tumor progression is when the tumor spreads to distant organs.
• Clinically detectable tumors are commonly associated with the escape phase.
• A neo-antigen is a mutated protein unique to cancer cells.
• During the equilibrium phase, the immune system continuously attacks the tumor but cannot eliminate it entirely.

Part 4: Physical and Molecular Inhibitory Mechanisms

• Cancer-Associated Fibroblasts (CAFs) create a protective collagen barrier around tumors.
• Tumor cells evade T-cell recognition by upregulating MHC-I.
• VEGF promotes angiogenesis in tumors.
• Tumors use VEGF to evade the immune system by reducing endothelial adhesion molecules.
• Tumor cells utilize mechanisms like upregulating FasL to induce immune cell apoptosis at a distance.
• Tumors interfere with immune cell navigation by producing antagonistic ligands for CXCR3.
• IL-10 suppresses T-cell function in the tumor microenvironment (TME).
• The Warburg effect is the preferential use of glycolysis, even in the presence of oxygen by tumor cells.
• Tumors become depleted of glucose due to the Warburg effect, and the byproduct lactic acid, contributes to the acidity of the TME.
• Hypoxia impairs immune cell activity due to their reliance on aerobic metabolism.
• Acidity in the TME impairs immune cell function and induces anergy.
• The tumor microenvironment (TME) favors the survival and growth of the tumor in several ways, impacting immune cells.
• The M2 macrophage phenotype facilitates these processes.
• Regulatory T cells contribute to tumor-promoting and immune evasion roles in the TME, actively suppressing certain immune cell types.