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Immunology Exam One > Innate Immune System > Flashcards

Innate Immune System Flashcards

1
Q

What is the first phase of the immune response?

A

Innate immune system

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2
Q

What are pattern recognition receptors (PRRs)?

A

Receptors of the innate immune system that recognize common molecular patterns on pathogen surface (PAMPs)

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3
Q

What are pathogen associated molecular patterns (PAMPs)?

A

Molecules specifically associated with groups of pathogens (not shared by host cells) that are recognized by cells of the innate immune system

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4
Q

What are the components of the innate immune system?

A

Complement proteins
Professional phagocytes (macrophages, neutrophils)
Natural killer cells
Dendritic cells

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5
Q

What are the major functions of the complement system?

A

Opsonization
Enhances bactericidal actions of phagocytes (complements activities of antibodies)
Kills pathogens (unlike antibodies)-makes MACs

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6
Q

What is the primary source that makes complement proteins?

A

Liver

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7
Q

Where are complement proteins highly concentrated?

A

Blood, tissues

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8
Q

What are the 3 ways to activate the complement system?

A

Alternative pathway
Lectin pathway
Classical pathway (antibody dependent)

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9
Q

What are facts about the alternate pathway?

A
  • Liver is showering the body with the production of complement proteins
  • Certain complement proteins spontaneously activate and attach to surfaces
  • Antibodies are not needed
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10
Q

What is the general order of steps in the alternate pathway?

A

-C3 spontaneously splits into C3a and C3b
-C3b: neutralized or bind to bad guy’s surface (amino or hydroxyl group)
-Complement protein B attaches to C3b
-C3b becomes C3Bb
-Complement protein D changes C3Bb to C3bBb
-C3bBb can split more C3 and C5 = more complement proteins to coat invader
-C3bBb interacts with C5, convertase splits C5 into C5a and C5b
C5b can combine with other complement proteins
-End result = Membrane Attack Complex (MAC), which drills hole in bacteria’s membrane

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11
Q

What are the chemoattractants and what do they do?

A

C3a and C5a

  • Attract macrophages and neutrophils
  • Activate macrophages and neutrophils
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12
Q

What are the three protection proteins?

A
  • MCP
  • DAF (delay accelerating factor)
  • Protectin
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13
Q

What does the protection protein MCP do?

A

Cleaves both C3b and C4b into inactive form

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14
Q

What does DAF (delay accelerating factor) do?

A

accelerates the destruction of convertase (C3bBb)

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15
Q

What does protectin do?

A

Removes MACs before they drill holes

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16
Q

What protein is involved in the Lectin Activation Pathway and what does it do?

A

Mannose-binding lectin protein (MBL)

  • Produced in liver
  • In blood and tissues
  • Activates the complement system by binding MASP (MBL associated serine protein) which clips C3 to make C3b
  • Lectin is a protein that attaches to a carb
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17
Q

What is the classical pathway?

A
  • Antibody dependent
  • Antibody binds to a bacterial surface, its tail (Fc region) provides a platform to activate C1
  • Once antibodies are produced, compliment activation is increased
  • Both compliment and antibodies coate pathogen and enables phagocytes to engulf and destroy
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18
Q

What are the professional phagocytes and what are their 2 main functions?

A
  • Macrophages and Neutrophils
    • Engulf and digest invading microorganisms
    • Induction of inflammatory response
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19
Q

Where are macrophages found?

A

Roam around in tissue

-Under skin, lungs, intestines

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20
Q

Where are neutrophils found?

A

Roam around in blood

21
Q

What are the 3 stages of macrophage readiness?

A

Resting
Activated or primed
Hyperactive

22
Q

What occurs with a resting macrophage?

A
  • Casually eating or snacking
  • Slowly proliferating
  • Express few Class II MHCs
  • Live for months in tissue
  • Circulate in blood, exit and differentiate in tissues to macrophages
23
Q

What occurs with a primed macrophage?

A
  • Eat much more
  • Express more Class II MHCs (function more as an antigen presenting cell)
  • Primed by any chemical signal ex. interferon gamma (IFN y)
  • Can produce complement proteins (C3, factor B, factor D)
24
Q

What occurs in a hyperactive macrophage?

A
  • Recieves a direct signal from a bad guy (LPS, mannose)
  • Stops proliferating
  • Focus all attention on killing
  • Grows larger
  • Increases rate of eating
  • Emits cytokines (TNF)
  • Increased number of lysosomes
  • Increased production of ROS
25
What are the main functions of macrophages?
Garbage collector while resting Antigen presenting cell and killer when activated Vicious killer when hyperactivated
26
What are the functions of neutrophils?
Incredible eaters Emit harsh chemistry Send out powerful signal molecules (TNF)
27
What are some facts about neutrophils?
- 20 million in blood - Short lived--5 days - Can exit blood and become activated in 30 min - Travel rapidly in blood - Must receive signal that bad guys are present - Roll, stop, exit for leaving blood
28
What are the 4 adhesion molecules?
SEL (selectin) SLIG (selectin ligand) ICAM (intracellular adhesion molecule) INT (integrin)
29
What is SEL (selectin)?
- Expressed by endothelial cells that line blood vessels after receiving alarm signals - Binds to selectin ligan (SLIG)
30
What is SLIG (selectin ligand)?
Expressed on surface of neutrophils (at all times)
31
What is ICAM (intracellular adhesion molecule)?
-Always expressed on lumen surface of capillary endothelial cells
32
What is INT (integrin)?
- Pre-made and rapidly transported to the surface of the neutrophil after being signaled - Strongly binds to ICAM
33
What is the order of events for rolling, stopping, and exiting neutrophils?
When macrophages are primed or hyperactivated they express signal molecules IL-1, TNF = let neutrophil know bad guy is present = cause sequence of events to allow neutrophil to exit blood -Capillary endothelial cells express selectin (SEL), which is stimulated by IL-1 and TNF -Neutrophil slows to sense this inflammation -SEL binds to SLIG -Neutrophil transports integrin (INT) to surface -Integrin binds to ICAM -Neutrophil stops -Neutrophil exits blood and enters tissue (attracted by C5a)
34
Why is the neutrophil cascade failsafe?
To safeguard against damage of selectin floods - Must have selectin before neutrophils invade - Must have integrin released before neutrophils invade
35
Where are most natural killer cells found?
blood, liver, spleen
36
What activates natural killer cells?
interferon, IL-12, IL-18
37
What are the 2 roles of natural killer cells?
1. Produce cytokines (like T helper cells do) | 2. FOrce infected or cancerous cells to commit suicide (can kill like CTLs)
38
What are the 2 ways natural killer cells can induce cell suicide?
Perforin/granzyme B | Fas ligand
39
What does perforin/granzyme B do?
``` Pokes a hold in the membrane like the complement system Inject enzymes (granzyme B) that cause cell to die (apoptosis) ```
40
What does the Fas ligand do?
Fas ligand on natural killer cell binds to Fas protein on invader Interaction triggers suicide (apoptosis) Fas is a transmembrane protein in the TNF family
41
What produces the "Don't Kill" signal to natural killer cells?
Natural killer cell receptors recognizing normal MHC I on target
42
What produces the "Kill" signal to natural killer cells?
Activating receptors (Pattern recognition receptors PRRs) - Bind to unusual carb or protein on cell's surface - Recognize molecule being produced by virus or cancerous cell - Also kills cells not expressing MHC molecules
43
What do IgG3 receptors do?
- Bind Fc region of IgG - Ab forms a bridge between target and NK cell - Causes NK cell to kill target (antibody-dependent cellular cytotoxicity)
44
Do natural killer cells have T cell receptors?
NO
45
What do natural killer cells do at rest?
Make some cytokines and can kill
46
What do activated natural killer cells do?
Make many more cytokines and are more effective killers
47
What are signals that activate natural killer cells?
- Lack of MHCs - LPS - Interferon alpha - Interferon beta - TNF from hyperactivated macrophages upregulates NK cell IL-2 receptors - IL-12 from primed or hyperactivated macrophages
48
When are interferons usually given off by cells?
When under a viral attack

Immunology Exam One (4 decks)

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