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BIOL 3553 Study Guide - Comprehensive Final Exam Guide - Protein, Immunoglobulin G, Cytokine


Department
Biology
Course Code
BIOL 3553
Professor
All
Study Guide
Final

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BIOL 3553

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Innate Immunity
Physical barriers colonized by commensal microorganisms protect against infection by
pathogens
o The outer parts of our body are parts where we would get a microbial infection. The
innate immune response is important as a barrier.
o Antimicrobial peptides are very small chains of amino acids and are really good at poking
small holes in microbes, eventually killing them
Intracellular and extracellular pathogens require different types of immune response
o The type of immune response activated depends on whether it is an extra or intracellular
pathogen. Most types of pathogens that would be inside the cell are viruses, there are
some bacteria that are intracellulr but most bacteria are extracellular.
Complement is a system of plasma proteins that mark pathogens for destruction
o Complement is a system of plasma proteins that mark pathogens for destruction
o C3 will be cleaved part of it will bind to the surface of the pathogen and enhances that
pathogen to be phagocytized (C3b) and C3a will recruit other cells.
o Small peptides released during complement activation induce local inflammation
o Antimicrobial peptides kill pathogens by perturbing their membranes
Cellular receptors of innate immunity distinguish ‘non-self’ from ‘self’
o Macrophages & Natural Killer Cells can phagocytose pathogens they comes across
o Tissue macrophages carry a battery of phagocytic and signaling receptors
o Recognition of LPS by TLR4 induces changes in macrophage gene expression
Activation of resident macrophages induces a state of inflammation at sites of infection
o The infection determines which cytokines are released.
o Some of the molecules you need to get into the infected tissue can do so if the blood
vessels are more permeable ( IL-1B. TNF)
o The higher temperature can help decrease microbial replication (IL-6)
o CXCL8 is a chemokine that is released from an infected area and recruits neutrophils to
the site of infections
o IL-12 is a cytokine that helps activates NKC and causes secretion of cytokines
Inflammatory cytokines recruit neutrophils from the blood to the infected tissue
Neutrophils are potent killers of pathogens and are themselves programmed to die
Inflammatory cytokines raise body temperature and activate the liver to make the acute-
phase response
o TLRs are primarily responsible for making cytokines
o IL-1/IL-6 and TNF are some of the main cytokines that are released.
o Opsonization C3 exists in the plasma and when it is cut in half you get C3A and C3B
which can be recognized by macropages and ENHANCE PHAGOCYTOSIS (<-
Opsonizaiton)
o IL Interleukin a protein that interacts with one leukocyte and has an affect on another
leukocyte
Toll-like receptors sense the presence of the four main groups of pathogenic
microorganisms
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o TLR4 interacts with gram - bacteria on plasma membrane of innate immune cell (good at
detecting things outside of the cell) extracellular
o TLR2 exists as a heterodimer mostly and recognizes gram + bacteria on plasma
membrane of innate immune cell (good at detecting things outside of the cell)
o TLR7 TLR8 TLR9 and TLR3 interact with viruses they exists on the surface of an
endosome (good at detecting things inside the cell)
o TLR5 recognizes flagella
o Innate immune cells TLR are germline encoded and can be found on the same
chromosome in all individuals
**Inflammation process:
o Cut in the skin so bacteria come in and activate cells that are in the tissue when the TLR
recognize the bacteria (macrophages, etc.)
o Mast cells have TLR on their surface too. When activated, mast cells produce and release
histamine which increases vascular permeability
o If gram bacteria interacts with macrophage will likely activate TLR 4 and CD14
o If gram + bacteria interacts with macrophage will likely activate TLR 2
o NFkB is a transcription factor in macrophages and will go into the nucleus to activate
cytokine production.IL-6, IL1-b and TNF are likely the cytokines made after a bacterial
infections (pyrogens)
o CXCL8 is a chemokine that is released from macrophages and has an effect on blood
vessels to recruit neutrophils to the area.
o Cytokines is a broad umbrella term a protein that is released from a cell. Chemokine is
a special kind of cytokine that attracts something to an area
o Cytokines released by macrophages activate selectins and integrin on endothelial cell
wall so the neutrophils can come from the blood vessels to the tissue
o The neutrophil will undergo apoptosis and then be phagocytosed by macrophages
5 cardinal signs of inflammation:
o Swelling
o Heat
o Redness
o Pain
o Loss of function (not always)
If you have really high levels of LPS going to the blood stream, you will activate all the cells in
all o the organs and you will have Sepsis excessive amount of cytokines released, neutrophils,
fever all trying to get rid of the gram bacteria .
If it was a viral infection, IFN alpha and beta are made much more.
Adaptive Immunity
o Host depends on innate immunity until acquired response
develops
o Primary response: first response to a particular antigen
o Remembers which mechanism was effective in
neutralising invader
o Anamnestic response: second response to same antigen
o enhanced antigen-specific response
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