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Immunology > Phagocytes and NK Cells > Flashcards

Phagocytes and NK Cells Flashcards

1
Q

Primary activators of the innate immune system, but NOT the first responder

A
  • sentinel cells
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2
Q

What cells are sentinel cells?

A
  1. Macrophages
  2. Dendritic Cells
  3. Mast Cells
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3
Q

Sentinel cells express Pathogen recognition receptors (PRRs) which can recognize?

A
  1. PAMPS - pathogen associated molecular patterns
    - on microbes
  2. DAMPS - damage associated molecular patterns
    - expressed on damaged host cells
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4
Q

Macrophages

A
  • sentinel and phagocytic cells
  • > can capture microbes and kill microbes
  • > can also be antigen presenting cells
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5
Q

The major antigen presenting cell

A
  • Dendritic cells
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6
Q

Plays a key role in allergies and can trigger inflammation

A
  • Mast cells
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7
Q

Types of Cytokines

A
  1. Interleukins
  2. Lymphokines
  3. Chemokines
  4. Interferons
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8
Q

Cytokines that act as growth and differentiation factors for cells of the immune system

A
  • Interleukins
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9
Q

Pro-inflammatory and chemotactic cytokines

A
  • Chemokines (IL-8)
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10
Q

Cytokines that can interfere with viral replication

A
  • interferons
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11
Q

Most important cytokines released by the sentinel cells are?

A
  • TNF, IL-1, IL-6

- > proinflammatory

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12
Q

Main result of cytokine release by sentinel cells

A
  • INFLAMMATION
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13
Q

What are phagocytic cells?

A
  1. Polymorphonuclear cells
    - granulocytes (neutrophils)
  2. Monocytes/Macrophages
    - monocytes when in the blood
    - macrophages when in the tissue
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14
Q

What are complement proteins produced by?

A
  • Macrophages and hepatocytes primarily
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15
Q

Chemical gradient to attract inflammatory cells

A
  • chemotaxis
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16
Q

Proteins that coats microbes and enhances phagocytosis

A
  • opsonins
17
Q

Integrins

A
  • surface protein molecules (adhesion proteins)

- active during chemotaxis to emigrate from vessels

18
Q

Phagocytosis Steps

A
  1. Chemotaxis
    - via chemokines and PAMPS
  2. Adherence
    - via receptors on the surface of phagocytes
  3. Ingestion
    - phagocytosis
  4. Destruction
    - oxygen dependent killing
    - oxygen independent killing
19
Q

Directed migration according to a chemical gradient

A
  • chemotaxis
20
Q

Receptor to bind complement opsonizing microbes

A
  • CR
21
Q

Receptors to bind antibody opsonizing microbes

A
  • FcR
22
Q

Neutrophil Enzymes

A
  1. Myeloperoxidase (MPO)
    - only cell with this, most potent antimicrobial
  2. Lysozyme
  3. Collagenases
  4. Lactoferrin
23
Q

First phagocyte to respond to infections after sentinel detection

A
  • Neutrophil
24
Q

Neutrophil characteristics

A
  • Short life span
  • dying neutrophils attract macrophages
  • not proliferative, there to kill and die (can not sustain killing)
  • > phagocytosis leads to death
  • active immediately after release from bone marrow
  • rapidly exhausted
25
Q

Monocytes/Macrophages characteristics

A
  • Long life span
  • maintain sustained phagocytosis
  • slower speed of response for phagocytosis
  • limited potent antimicrobial capacity
  • > less degranulation and no MPO in most mammals
  • tissue repair
  • activated AFTER exposure to bacterial proteins (PAMPS) and inflammatory molecules (cytokines)
  • “PACMAN”
  • essential for homeostasis (recycling RBCs) and recovery
26
Q

What almost exclusively makes IL-8?

A
  • neutrophils
27
Q

Which cells secrete Cytokines?

A
  • Sentinel cells
  • > TNF, IL-6, IL-1
  • > IL-8 (chemokines)
  • Macrophages
  • > TNF-a, IL-1, IL-6, IL-12!!
28
Q

What are the major cytokines of Macrophages

A
  1. IL-1
  2. IL-6
  3. IL-12 (acts on T and NK Cells)
  4. TNF-a
29
Q

NK cells

A
  • cells of the innate immune system
  • kill virally infected host cells and tumor cells
  • > antigen independent, whereas cytotoxic T cells (CTLs) are antigen dependent
  • > kill host cells infected with microbes, not microbe directly
  • can express FcR and bind to antibody
  • receptor for some complement proteins
  • MHC-1 Expression by host cells inhibits
  • recognize proteins on target cells expressed under stress
  • regulated by cytokines
30
Q

Antibody dependent cell-mediated cytotoxicity (ADCC)

A
  • if target host cell has antibody attached to it
  • > expresses FcR so can bind to antibody
  • kills host cell with cytotoxic granules
31
Q

Effect of MHC-1 Expression by host cells on NK cells

A
  • NK cells are inhibited by cells that express MHC-1
  • > says “im normal leave me alone”
  • > if does not express the NK cell will see and kill it

Immunology (14 decks)

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