Innate Immunity Flashcards
Name the two different type of phagocytes of the innate immune system.
Macrophages/monocytes
Neutrophils
Where are macrophages found?
Macrophages are long-lived leukocytes which are widely distributed in normal tissues.
What is the most abundant type of white blood cell in circulation?
Neutrophils
Are neutrophils found in normal tissue?
No- they are rarely found in normal tissue. They are only recruited following activation of other immune system components.
What is opsonization?
The coating of particles by molecules that enhance recognition by phagocytes
The adaptive immunity can opsonize pathogens with antibodies.
The innate immune system can opsonize pathogens with proteins of the compliment system
What is the life span of a neutrophil?
Short-lived
What is a PAMP?
PAMP: Pathogen Associated Molecular Pattern
-epitope from foreign particle
What is a DAMP?
DAMP: Damage Associated Molecular Pattern
-epitope of endogenous protein, from a damaged cell
What is the innate immune system’s response to binding PAMPS and DAMPS with their PRRs?
The innate immune system upregulates their expression of pro-inflammatory cytokines and antimicrobial peptides
Name four classes of PRRs
Toll-like receptors
NOD-like receptors
C-type lectin-receptors
Rig-I-like receptors
Are all PRRs expressed on the cell surface?
No-depending on what they recognize, PRRs can be located extracellularly (for bacterial PAMPS), or in the cytosol (for viral infections etc)
What do the C-type Lectin PRR’s recognize and bind?
Mannose (on bacterial glycoproteins)
Compliment activation (by all three pathways) leads to what effector function?
Enhanced phagocytosis through recognition of the C3b deposited all over the pathogen surface
How is the phagocytic function of dendritic cells different from other phagocytic cells?
Dendritic cells do not destroy the target, but rather preserve the microorganism material for presentation to the adaptive immune system
What is the role of NADPH in the phagolysosome?
NADPH, present in the phagolysosome membrane is oxidized by NADPH oxidase causing respiratory burst of superoxide (O2-, H2O2, and OH-) causing death of engulfed microbes
What two cells are the major antigen presenters to T cells?
Macrophages and dendritic cells
Differentiate the origin of the epitopes presented by class I MHC from Class II MHC
Class I: endogenous proteins
Class II: exogenous proteins
What are innate lymphoid cells? How are they different from B and T cells?
Lymphocytes by morphology, but different from T and B cells in that they
1) Lack RAG genes –> No DNA rearrangements
2) They lack myeloid/DC markers
3) THey are of lymphoid morphology
—-? Weird slide.
What are the three different types of innate lymphoid cells?
ILC1, ILC2 and ILC3
They are differentiated by the cytokines produced
Describe the cytokines produced by innate lymphoid cells type 1 (natural killer cells)
NK cells secrete the pro-inflammatory cytokines IFN-gamma and TNF
What is the purpose of the innate immune system releasing cytokines and chemokines following binding of PAMPS/DAMPS by PRRs?
Activation of effector cells (mast cells, innate lymphoid lymphocytes) which can amplify the signal and activate the adaptive immune system
What is the result of a problem with PRRs?
Failure of PRRs –> susceptibility to bacterial and viral infections. If the innate immune system is not activated, the adaptive immune system will not respond properly
