Immunology and Cancer Quiz

Immune System in Health and Disease

• Innate immunity is fast, but limited in strength
• Involves macrophages and natural killer (NK) cells
• Adaptive immunity is slower but highly effective
• Involves B and T lymphocytes
• Takes time to develop, but provides powerful specific responses
• Has memory, so subsequent infections are faster. The response is much stronger
• First infection results in pathogen proliferation, disease, and symptoms, while subsequent infections, because of memory, will be faster, causing little to no symptoms

Principle of Vaccination

• Primary vaccination response is characterized by a short lag (1-4 days) and an early peak (3-5 days) of antibody production.
• Subsequent vaccination leads to a stronger response (100-1000X) and a longer duration
• Secondary response involves memory B cells and is highly similar to the response from the first infection

Somatic Hypermutation

• V region activation by enzyme for affinity selection for high affinity
• Antibodies produced have higher affinity

Isotype Switching

• Change in recombination in immunoglobulin formation
• Middle part is spliced to form the IgM molecule, then VDJ genes can join with gamma genes to form IgG
• Occurs in B cells, and switching occurs between different antibody classes (isotypes) like from IgM to IgG.

Immune Response to Infections

• Pathogens can be extracellular or intracellular
• Extracellular pathogens include fungi, yeasts, molds, parasites, worms, protozoa
• Intracellular pathogens include viruses (as viruses replicate inside living cells)

Humoral Responses

• Non-specific responses include: complements, acute phase proteins, histamine.
• Specific responses include: antibodies, B cell derived effector molecules, opsonization, and neutralization (of viruses, toxins)

Cell-Mediated Responses

• T-dependent, non-specific responses include: phagocytes, macrophages, natural killer (NK) cells
• CD16+ CD56dim/neg: cytotoxic NK cells (90%)
• CD16-CD56 bright: regulatory or cytokine-secreting NK cells
• Similar to cytotoxic T cells (CD8+) and helper T cells (CD4+)

Mechanisms of Target Cell Killing by T and LGL

• T-dependent, specific cytotoxic T cells kill infected cells
• Helper T cells help other cells

Cytokine-Mediated Direct Target Cell Killing

• TNFα/β and IFNγ directly kill cells

Phagocytes

• Non-specific, innate part
• Neutrophils circulate in blood and move to infection sites.
• Chemotaxis induces cell movement in a specific direction
• Complement attracts phagocytes to approach bacteria
• Reactive oxygen intermediates (ROIs)
• Reactive nitrogen intermediates (RNIs)

Defects in Immune System

• Defects in immunoglobulins, complements, phagocytosis
• Infections, e.g. AIDS (HIV infects Th cells), drugs, radiation, malnutrition
• Primary immunodeficiencies, most genetic, linked to T cells or B cells (e.g. SCID)
• Traditional T and B cell deficiencies, or both (e.g. T and B cell deficiencies)
• Defects in components necessary for phagocyte function like NCF1 and NCF2
• X-linked deficiencies are the most severe (70% of the cases). These are defects in an enzyme NADPH oxidase which produces reactive oxygen intermediates

Immunity against Infectious Agents

• Immunity against "non-self" and "self" (autoimmunity)
• Genetic mutations, viral infections, chemical carcinogens, radiation, immunodeficiencies,
• Vaccines against viruses prevent some cancers

Immune Escape Mechanisms of Tumors

• Tumor-cell surveillance theory
• Tumor cells use mechanisms to escape detection and destruction. These cells have molecular mechanisms to break from detection and destruction by immune cells, to aid in the proliferation of the tumor
• Lack of important molecules for the immune system, tumor-derived factors that suppress immunity

Immune Checkpoint Inhibitors

• PD-L1 binds to PD-1 and inhibits T-cell killing of tumor cells
• Blocking PD-L1 or PD-1 allows T-cell killing of tumor cells
• These are treatment approaches that aim to enhance the immune system by blocking these proteins as they interfere with the functioning of the immune cell

Immunopathologic Responses and Hypersensitivity

• Systemic hypersensitivity reactions like anaphylaxis are often initiated by allergens
• Allergens can bind to IgE and trigger strong reactions in some individuals (e.g. allergic reactions to bee venom)

Autoimmunity

• Adaptive immune response directed against self antigens
• "Self"/“non-self” concepts are crucial to understanding adaptive immunity.
• Tolerance mechanisms regulate these responses to avoid the body attacking itself (autoimmunity)

Test your knowledge on the immune system's role in cancer, including mechanisms of tumor development and immune response. This quiz covers various topics, such as types of immunity, tumor evasion strategies, and the impact of immune checkpoint inhibitors. Enhance your understanding of how immunology intersects with cancer treatment.