3- Innate Immunity Flashcards
At what point in life do you have all of the innate immunity mechanisms you will have?
Birth
Active proliferation of macrophages in response to infection.
They DON’T proliferate in response to infection. But, the DO localize to the area of the infection (and as such will be found in high #’s at injury/inflammation sites.
What is the general result of the Innate Response?
INFLAMMATION
This is a fundamentally protective process that tries to destroy or contain pathogens but can be destructive if not controlled.
General mechanism of inflammation and one major result.
Alteration of blood flow and increased vascular permeability. This leads to INFILTRATION OF WHITE CELLS into the area of reaction.
How is the Innate Response initiated?
Recognition of PAMPs or DAMPs via Pattern recognition receptors (PRRs).
Effect of PRR binding to PAMPs and DAMPs
Expression of proinflammatory cytokines and antimicrobrial proteins
The 4 classes of PRRs and what they recognize
TLR- sense extracellular pathogens (bacteria)
C-type Lectin Receptors- recognize sugars that pathogens have on their surfaces
Rig-I Like Receptors- recognize viral RNA molecules
NOD-like Receptors- intracellular recognition of viruses and bacteria (mostly DAMPs)
2 main methods used by TLR to sense bacteria (specially used by TLR-4)
LPS (major method)- used to sense gram-negative bacteria
Lipoteichoic acids- used to sense gram-positive bacteria
What is the most common terminus for PAMP-TLR binding?
PAMP-TLR binding activates intracellular downstream signaling pathways. The most common terminus is NF-kB
Why can TLR deficiencies cause such significant issues?
Because many different receptors uses TLRs as channels so an issue this upstream can have many downstream effects. Issues with TLRs can result in very severe immunodeficiencies.
Why are Dendritic Cells often viewed as the most import cell in the immune system?
They are responsible for the transition from innate to adaptive immunity via presentation of antigens and PRR stimulation.
They can additionally customize and direct the type of immune response based on how they present.
A major difference between NK T-cells and Gamma-Delta T-cells
NK cells recognize lipid antigens, whereas gamma-delta cells recognize phospho-antigens
Trained immunity characteristics of the Innate Response
The innate immune system can respond to a secondary infection in a way which is more efficient than how it responded to the first. This is due to some level of training via epigenetic changes– genes which are important for a faster response are more quickly expressed.
