Immune system Flashcards
What are the two immunities that make up the immune system?
Innate immunity and adaptive immunity
What does the innate immune system do?
Provides the body’s first line of defense against infectious agents
What defensive barriers are involved in the innate immunity?
Anatomic and physical Physiologic Complement Cellular Inflammation
Give examples of anatomic and physical barriers of the innate immunity.
Examples: skin, mucus membranes and normal flora
Give examples of physiologic barriers in the innate immunity.
Examples: temperature, pH, anti-microbials and cytokines
Give examples of cellular defenses in the innate immunity.
Examples: phagocytes and granulocytes
What characteristics do the innate immune defenses have in common?
- Present intrinsically with or without previous stimulation
- Have limited specificity for shared microbe and cellular structure (pathogenic associated molecular patterns [PAMPs] and damage-associated molecular patterns [DAMPs]
- Have limited diversity as reflected by a limited number of pattern recognition receptors
- Are not enhanced in activity upon subsequent exposure- no memory
What are the components of the adaptive immune response?
B and T lymphocytes and their effector cells
What produces the heavy chain variable domains?
VDJ recombination
What produces the light chain variable domains?
VJ recombination
What gene is required for making the enzyme that is required to make the VJ recomination?
Rag1 and Rag2
What does terminal deoxyribonucleotidy transferase (Tdt) do?
Randomly inserts bases on the heavy chain while it is undergoing recombination. Not active during light chain recombination in B cells.
Active during the rearrangement of all gene segments in the formation of the TCR
What do T lymphoctes bind on their TCR?
Peptides and only peptides
What does the inflammasome secrete when it is activated?
Produces IL-1-beta and IL-18
Characteristics of Neutrophils
- Circulating phagocytes
2.Short lived - Rapid response, not prolonged defense
These are the first to arrive
Characteristics of Monocytes/Macrophages
- Monocytes circulate in the blood, become macrophages in the tissues
- Provide a prolonged defense
- Produces cytokines that initiate and regulate inflammation
- Phagocytose pathogens
- Clear dead tissue and initiate tissue repair
- Macrophages will develop along one of 2 different pathways
Characteristics of Dendritic cells (DCs)
- Found in all tissues
- Antigen processing and presentation (APC)
- Two major functions: initiate inflammatory response and stimulate adaptive immune response
Characteristics of Mast cells
- Found in the skin and mucosa
2. Two pathways for activation: innate TLRs and antibody-dependent (IgE)
Characteristics of Natural killer cells (NK cells)
- Found in the blood and periphery
- Direct lysis of cells
- Secretes IFN-gamma
What is chemotaxis and who does it?
Chemotaxis:
Recruitment of inflammatory cells and anaphylatoxins
Complement proteins:
C3a, C4a, and C5a
What is opsonization of pathogens do and who does that?
Opsonization of pathogens makes it easier for them to be phagocytosed and killed
Complement protein:
C3b
How does the complement system kill pathogens and who does that?
Puts holes in the membrane
Done by membrane attack complex (MAC) which is made up of C5b, C6, C7, C8, and C9
What is the alternative pathway for activating the complement pathway?
Lectin-binding or mannose-binding pathway (MBP)
Mannose-binding leptin binds to carbohydrates on the pathogen. Activates C3 of the complement pathway
Part of innate immunity.
What are the 4 steps of the acute inflammatory response?
Step 1: Rolling
Step 2: Activation by chemo-attractants
Step 3: Arrest and adhesion
Step 4: Transendothelial migration (extravasation)
What are the chemoattractive molecules?
Chemokines (IL-8)
Complement protein C5a
Leukotriene B4
Formyl methionyl peptides (F-met)
What are the proinflammatory cytokines?
IL-1 IL-6 TNF-alpha IL-12 IL-8
What cytokines cause fever?
IL-1
IL-6
TNF-alpha
What cytokines are anti-inflammatory?
TGF-beta
IL-10
What cells are in the cortex of the lymph nodes?
B-cells (memory cells)
What cells are in the paracortex of the lymph nodes?
T-cells
What cells are in the medulla of the lymph nodes?
Plasma cells
What happens in the germinal center of the lymph nodes?
- Class switching
- Somatic hypermutation
- Plasma/memory cells
What cells are in the marginal zone of the spleen?
B-cells
What cells are in the peri-arteriolar lymphoid sheaths (PALS) in the spleen?
T-cells
What MHC is loaded in the exogenous pathway?
Pathogens are outside cells
MHC II
What MHC is loaded in the endogenous pathway?
Pathogens are inside cells
MHC I
What MHC do CD8 T-cells bind to?
MHC I
What MHC do CD4 T-cells bind to?
MHC II
What MHC does NK cells look for?
MHC I
What is the naive helper T (Th) cell?
Th0
What are the different subsets of Th cells that come from the naive Th cell?
Th1
Th2
Th17
What does Th1 respond to and secrete?
Responds to:
Intracellular infections
Secretes: IFN-gamma
What does Th2 respond to and secrete?
Responds to:
Parasitic infections
Secretes:
IL-4, IL-5, IL-10, IL-13 and TGF-beta
What does Th17 respond to and secrete?
Responds to:
Extracellular bacterial and fungal infections
Secretes:
IL-17 and IL-22
What is the signal that makes the Th0 differentiate into the Th1?
IL-12
What is the signal that makes the Th0 differentiate into the Th2?
IL-4
What is the signal that makes the Th0 differentiate into Th17
IL-23, IL-6 and TGF-beta
What does the CD8 T-cell differentiate into?
Cytotoxic T lymphocytes (CTLs)
What do CTLs do?
Kill cells
What antibody can cross the placenta?
IgG
What receptor bind IgA to make it a dimer?
poly-Ig receptor
Where is IgA mainly?
In the lamina propria
What is the first antibody made?
IgM
What signal produces IgG?
IFN-gamma by Th1 cells
What signals produce IgA?
TGF-beta and IL-5
What does IgM and IgG do?
They activate the complement pathway
What does IgA do?
A neutralizing antibody that inhibits binding of toxins or pathogens .
Does not activate complement pathway, act as opsonin or mediate ADCC
What does IgE bind to?
Binds to Fce receptors present on mast cells, eosinophils and basophils
What does IgE protect against?
Protective immune response against parasites and allergens.
Does not activate complement or act as an opsonin
What are the effector mechanism?
Perforin, granzymes and cytokines
