Non-Specific Cellular Barrier - Innate Immunity/2LoD Flashcards
What are the 4 types of cellular barriers?
- Granulocytes (neutrophils, eosinophils, basophils)
- Macrophages
- Dendritic cells
- Natural Killer cells
Where in the body are granulocytes produced?
In bone marrow
What are the key differences between neutrophils and macrophages?
Rapid phagocytosis but not repeatedly (N) vs. slow phagocytosis but repeatedly (M); short-lived (N) vs. long-lived (M); not APCs (N) vs. are APCs (M)
What generates enzymatic activity during neutrophil phagocytosis?
O2 consumption by NADPH oxidase
What are the 3 bacterial enzymes in neutrophil granules?
Lysozymes, myeloperoxidase, and superoxidase
Define and describe the differences between neutrophilia and neutropenia.
Neutrophilia: higher than normal neutrophils = WBCs are fighting off infection
Neutropenia: lower than normal neutrophils = infection is overpowering the I.S.
Phagocytosis, respiratory burst, and extracellular traps (NETs) are all examples of what?
Of how neutrophils kill invading pathogens
What are the 4 steps of neutrophil phagocytosis?
- Chemotaxis
- Attachment
- Phagocytosis
- Destruction
What is diapedesis?
The process by which neutrophils migrate out of systemic circulation and enter the injured site via the gap created between endothelial cells
How do opsonin proteins facilitate neutrophilic phagocytosis?
By decreasing the zeta potential between the neutrophil and antigen (both cells’ surfaces are negatively charged)
How is a phagosome created?
Neutrophil engulfs the pathogen, creating a vacuum –> phagosome (pathogen trapped within neutrophil)
What occurs during formation of the phagolysosome?
lysosome granules (lysozymes) fuse with the phagosome, and destruct the pathogen by secreting antimicrobial fluids
When would eosinophilia be seen?
Allergies and parasitic infestations
Describe the contents of an eosinophil granule.
A major basic protein (MBP) within a matrix surrounded by proteins with cytotoxic and pro-inflammatory capabilities.
How do basophils affect blood pressure?
They contain a complex of vasoactive molecules which affect blood vessel diameter
When would basophilia be seen?
Cancer
Describe the 3-step process of macrophage formation.
Exist as monoblasts in bone marrow –> mature into monocytes/enter systemic circulation –> differentiate into macrophages when complement system recruits the phagocytic molecule into the injured tissue
What is a distinguishing feature of an activated macrophage’s nucleus?
enlarged cytoplasm
What produces interleukin (IL) proteins?
Macrophages and dendritic cells
IL-1, IL-6 and TNF factor alpha are all pyrogenic cytokines. How do these proteins affect the body and fight off pathogens?
Increased body temp –> decreased [antigen] // decreased infectious bacterial growth.
Increasing body temp is energy-consuming, so it also makes you tired
Why do pyrogenic cytokines reduce appetite?
Reduced appetite decreases the chances of bacterial entry through G.I. tract
Pyrogenic cytokines (increase or decrease):
___ neutrophils in blood
___ motility of neutrophils
___ alternate pathway of complement system
___ lymphocyte activation
facilitating bacterial elimination by macrophages
“increase” for all
An antigen causes tissue damage. What is IL-1’s role in assisting with tissue repair?
stimulates fibroblast proliferation which produces collagen
T-cell and B-cell activations are tightly controlled processes (bad for I.S. to be “on” all the time; constant inflammation leads to chronic inflammatory diseases). How do they get activated?
By antigen-presenting cells - present a processed antigen (antigen post phagocytosis) to T cell or B cell
Which APC is more potent- macrophages or dendritic cells?
Dendritic cells
Where are antigen-presenting dendritic cells located?
Epithelial tissue of skin (a.k.a. Langerhans cells)
How do natural killer (NK) cells kill infectious antigens?
Contain perforin and proteases (granzymes) which are secreted by NK cells and perform cytotoxic activities
What interleukin do NK cells secrete?
Interleukin Tumor Necrosis Factor Alpha (IFN alpha)
