Lecture 1: Adaptive and Innate Immune Responses Flashcards
Q: What are the main types of physical barriers in the immune system?
A: Skin and mucous membranes (e.g., respiratory tract, GI tract, urogenital tract)
Q: What are the characteristics of innate immunity?
A: Immediate response, non-specific, no memory, uses pre-primed cells
Q: What are polymorphonuclear cells (PMNs)?
A: Immune cells with multi-lobed nuclei: neutrophils, eosinophils, basophils
Q: What is the role of neutrophils?
A: Rapid responders, kill via oxidative burst, form pus (green from myeloperoxidase)
Q: What do eosinophils target?
A: Parasitic infections and allergic responses
Q: What is the role of basophils?
A: Involved in allergic responses, release histamine
Q: What are monocytes?
A: Phagocytic cells that become macrophages; also present antigens
Q: What is the oxygen-independent killing pathway?
A: Uses lysosomal enzymes (e.g., proteases, phospholipases) to digest microbes
Q: What is the oxygen-dependent killing pathway?
A: Uses reactive oxygen species (ROS) like bleach (HOCl) to kill microbes
Q: What is the role of myeloperoxidase?
A: Enzyme in neutrophils that produces ROS and gives pus a green color
Q: What are three ways NK cells kill target cells?
A:
Fas ligand interaction → Caspase-3 → Apoptosis
Perforin + Granzyme → Caspase-3 → Apoptosis
Antibody-dependent cellular cytotoxicity (ADCC)
Q: What is the role of caspase-3 in cell death?
A: It’s the main executioner enzyme in apoptosis
Q: What cells are part of the adaptive immune system?
A: T cells, B cells, NK cells (also have innate-like functions)
Q: Which antibody is first produced in response to infection?
A: IgM (low affinity, high avidity)
Q: Which antibody is found in mucosal surfaces?
A: IgA (especially in GI and respiratory tracts)
Q: Which antibody is involved in allergy and asthma?
A: IgE (very low baseline levels)
Q: What makes dendritic cells “professional APCs”?
Q: What are antigen-presenting cells (APCs)?
A: Dendritic cells, macrophages, B cells
A: Constantly sample environment, migrate to lymph nodes, highly efficient at presenting antigen
Q: Why don’t neutrophils act as APCs?
A: Short lifespan (6–18 hours), insufficient time to migrate and present antigen
Q: What are cytokines?
A: Growth factors that modulate immune cell activity (e.g., TNF, IL-1, IL-6)
Q: What are chemokines?
A: Cytokines that guide cell migration (e.g., IL-8 attracts neutrophils)
Q: Which cytokines are key in inflammation?
A:
TNF: Increases adhesion molecules
IL-1: Induces fever
IL-6: Acute-phase response
IL-12: Activates NK cells, increases IFN-γ
IL-17: Recruits neutrophils & monocytes
IFN-γ: Activates macrophages
Q: What is the central protein in the complement cascade?
A: C3, cleaved to C3a and C3b
Q: What are the three complement activation pathways?
A:
Classical (via IgG/IgM + C1)
Alternative (directly by microbial surfaces)
Lectin (mannose-binding lectin binding microbes)
Q: What are the functions of complement proteins?
A:
C3b: Opsonization
C3a: Chemotaxis
MAC (C5-C9): Lysis of microbes
