Immuology (Week 2 and 3) Flashcards
Cells of the immune system (3 categories)
Granulocytes: neutrophils, eosinophils, basophils, mast cells
Myeloid cells: monocyte/macrophage, dendritic cell
Lymphocytes: NK, Th, CTL, B, Plasma cell
4 chemical components of the immune system (4 C’s)
Cytokines- Interleukins, interferons, TNF, colony stimulating factor
Compliment-attack extracellular pathogens
Chemokines-leukocyte migration to target site
Coagulation -blood clotting; can modulate immune response
the immune system is a _____organ and ____ _____ unit
sensory organ
special forces unit
Physical barrier defense:
skin, mucosal epithelia, coughing vomiting
Chemical barriers:
pH of body fluids, secreted fatty acids, antimicrobial peptides, ROS
Restricted germline-encoded receptors:
TLR (PRRs: pattern recognition receptors). Each TLR recognizes one type of microbial component.
What are PAMPS/DAMPS?
Pathogen-associated molecular patters
Damage-associated molecular patterns
Where are PAMPS expressed?
cell surface and intracellularily (ex. viruse PAMPS are recognized by intracellular TLRs, same with intracellular bacteria)
PAMP/DAMP + TLR=
downstream signaling cascade that results in function of innate cell to deal with the danger (cytokine expression and release, phagocytosis etc. )
What is the inflammasome?
multiple cytoplasmic molecules assembled in pinwheel; sensor of danger signals (PAMPS, DAMPS). ex. : results in secretion of IL-1
What are the ‘professional phagocytes’ ?
neutrophils, macrophages, dendritic cells, B cells
Name the different types of recognition receptors on the surface of macrophages:
- mannose receptor
- compliment receptor (binds compliment)
- Fc receptor (binds antibodies)
- TLR (PRR)
Phagocytosis leads to…
degradation, processing, presentation of antigen (T cell activation), induces pro-inflammatory cytokine release.
Mechs for pathogen elimination:
- phagocytosis
- compliment cascade
- ADCC (antibody- dependent cell-mediated cytotoxicity)
- defensins
- pentraxins
What does activated compliment do? (3 things)
- recruits inflammatory cells
- opsonization of pathogens
- killing pathogens
What does the ADCC- antibody dependent cell-mediated cytotoxicity do? What cells do this?
- Kills opsonized target cells (covered w Abs)
- NK cells, neutrophils, eosiniphils
What are tissue sentinel cells?
What do they express?
Are they recruited first?
- mast cells and epithelial cells
- PRRs (recognize PAMPS for fast response)
- Yes, they are first to be recruited.
After the tissue sentinel cells, who arrives on the scene?
Neutrophils (PMN)
Describe neutrophils (PMN).
- large reserve in bone marrow
- circulate in blood until called on to enter infected tissue
- dedicated killers (phagocytose)
- short-lived (die–> Pus.
What is the order of innate cells on the scene? TSC, Macrophages, Neutrophils
TSC, Neutrophils, Macrophages
What doe macrophages do?
- Suppress PMN efflux
- phagocytose pathogens and PMN debris.
At sites of inflammation, what pro-inflammatory cytokines do macrophages secrete?
IL-1B: activates vascular endothelium, activates lymphocytes, local tissue destruction, increases access of effector cells–> fever, production of IL-6
TNF-a: activates vascular endothelium, increases permeability (inc entry of IgG, compliment, cells to tissue), inc fluid drainage to lymph nodes–> fever, mobilization of metabolites, shock.
IL-6: lymphocyte activation and increased Ab production –> fever, induces acute-phase protein production by hepatocytes
CXCL8: chemotactic factor recruits neutrophils/basophils/T cells to infx site
IL-12: activates NK cells, induces differentiation of CD4 cells into TH1 cells.
What organs do IL-1, IL-6, TNF-a act on (what do they do)?
Liver: Acute-phase proteins (C-reactive protein, mannose binding protein)–> activation of compliment, opsonization
Bone-marrow endothelium: neutrophil mobilization–> phagocytosis
Hypothalamus: increased body temperature–> decreased viral + bacterial replication, increased antigen processing, facilitates adaptive immune response
Fat, muscle: protein and energy mobilization to generate increased body temperature–> ‘’
Dendritic cells: TNF-a stimulates migration to lymph nodes and maturation–> initiation of adaptive immune response
What do Natural Killer Cells do?
- killer lymphocytes of innate immune response
- provide innate immunity against intracellular infx, esp virus
- cytokine production
- killing fnx (ADCC)
