Flashcards in Innate Immunity Deck (34):
What is the innate immune system?
It is the non-adaptive immune system to defend the host against pathogens. It exists in the germ line and does not undergo any genetic rearrangements.
What are the main cells of the innate immune system?
What are the two major types of phagocytes found in the innate immune system?
What are some of the characteristics of macrophages?
-are long-lived leukocytes.
-are widely distributed in normal tissues.
-are often the first cell to encounter a pathogen.
-represent the mature form of circulating monocytes.
-increase in number at sites of injury or infection.
What are some of the characteristics of neutrophils?
-are short-lived circulating leukocytes.
-are the most abundant type of white cell in the circulation.
-are rarely found in normal tissues.
-can be quickly recruited to sites of injury or infection.
What does it mean if neutrophils are seen in high amounts in tissues?
There is likely some sort of problem present in the tissue
What is opsonization?
Opsonization is the coating of particles by molecules that enhance recognition by phagocytes.
Adaptive immunity can opsonize pathogens with antibodies. The innate immune system can opsonize pathogens with proteins of the complement system.
What is the function of cytokines and what innate cells produce them?
Macrophages make them to act on cells to program them for microbial combat
What is the function of chemokines and what innate cells produce them?
Macrophages make them with chemoattractant properties to recruit leukocytes to sites of infection
What is the function of lipid mediators?
They have a similar function to cytokines in reprogramming cells
What are cell surface PRRs?
PAMP recognition receptors
Where are PRRs highly expressed?
Macrophages and dendritic cells
What is the function of TOLL like receptors?
Transmembrane and sense extracellular
infection like bacteria
What is the function of C-type lectin receptors?
Transmembrane and sense sugars for fungal infections
What is the function of Rig-I like receptors?
Cytosolic and recognize viral RNA
What is the function of NOD like receptors?
Cytosolic and recognize bacteria and viruses that enter the cell
What is inflammation?
Inflammation is a general term for the accumulation of fluid, plasma proteins and white blood cells that occurs in tissue subjected to injury, infectious agents, or immune responses.
What are the effects and purposes for inflammation?
Inflammation is fundamentally protective and is intended to destroy or wall off the offending agent.
It is interwoven with tissue repair but can be destructive if it goes on too long.
What are the 3 key events in inflammation?
-Alteration of blood flow
-Increased vascular permeability
-Infiltration of WBCs
What is alteration of blood flow in inflammation?
Vasodilation will occur and increased blood flow to the tissue will result (calor, rubor, dolor)
What is the increased vascular permeability in inflammation?
Endothelial cells contract and allow for the leakage of more serum into the tissue space (tumor)
What is the infiltration of WBCs in inflammation?
Neutrophils move in early on then macrophages and lymphocytes come to the site last.
What activates the innate immune system and how fast is this response?
It occurs within minutes and is activated by Pattern recognition receptors (PRRs) on DC or macrophages.
What are the various types of PRRs?
What does the TLR-4 PRR specifically respond to?
What happens when a PRR is activated?
Common characteristics of TLR activation are downstream signaling pathways in phagocytes/DC.
The final common path for pro-inflammatory activation is NF-kB. Activation of transcription factor NF-kB activates genes encoding pro-inflammatory cytokines
What is the function of dendritic cells in the innate immune system?
They roam around the body and phagocytize to become antigen presenting cells. This will direct the type of adaptive response that occurs.
What is the function of the natural killer cells in the innate immune system?
Lymphocytes in the blood that can directly kill the target infected cell or cancerous cell
What are NK T cells?
They are not natural killer cells and are instead a subset of T cells as they have a T cell receptor that is restricted to glycolipid (instead of peptide) antigens.
What are gamma/delta lymphocytes?
They recognize small molecule phosphoantigens which are metabolic intermediates in lipid biosynthesis in bacterial but not in mammals under normal circumstances.
How can the innate system have "memory?"
The innate system can be trained to remember an infection so that it can respond more strongly and quickly during secondary infections.
This occurs via epigenetic changes that result in perpetual activation of genes necessary to support the increased metabolic activity of these trained cells.
What are PMNs?
What is cellular immunity?
It is a process during which host effector cells are induced to kill pathogens directly