Lecture 2: Innate Immunity I

Question 1

_________ exists across all types of organisms in a variety of ways

Answer 1

Immunity

Question 2

Nonspecific defenses (Innate Immunity)

Answer 2

1st line: skin, mucous membranes, chemicals

2nd line: Phagocytosis, complement, interferon, inflammation, fever

Question 3

Specific defenses (Adaptive Immunity)

Answer 3

3rd line: Lymphocytes, antibodies

Question 4

Fundamentals of Innate Immunity (3)

Answer 4

1. Protective mechanism that exists before infection
2. Rapid responses encoded within the germline (DNA in egg and sperm cells)
3. Responses are typically identical upon repeat infection. No improvement on innate immune response

Question 5

Innate immune cells

Answer 5

Ready to act immediately

Question 6

What is a limitation of innate immunity?

Answer 6

No memory

Question 7

How long does it usually take for an innate immune response?

Answer 7

6-12 hours

Question 8

Example of cells involved in innate immunity?

Answer 8

Phagocytes, Dendritic cells, Complement cells, Natural killer cells

Question 9

Inflammation

Answer 9

Mobilizing bodily defenses at sites of infection.

Happens when there’s pathogen present

Question 10

What happens during an inflammation?

Answer 10

• vasodilation
• increase in capillary permeability
• influx of immune cells to affected tissues

Question 11

4 Signs of Inflammation

Answer 11

1. Redness- vessels dilate (vasodilation) and blood volume increases
   - appear more red because there’s more RBC; more WBC too
2. Heat- increased blood volume brings warmth to affected tissue
3. Edema- swelling due to accumulation of fluid from blood in affected tissue
4. Pain- some inflammatory mediators trigger the pain response

Question 12

Evidence of Inflammation: Elie Metchnikoff (1800s)

Answer 12

• insult to starfish larvae with thorn. Starfish have innate immunity
• rapid localization of cells to site of insult
• breakdown of thorn by cells
• first observation of process known as phagocytosis

Question 13

Processes involved in inflammatory response

Answer 13

1. Margination- migration of WBCs toward the endothelium during blood flow
2. Diapedesis- leukocytes squeezes in amoeboid fashion across the endothelial cells
3. Chemotaxis- directed migration of a cell in response to a chemical stimulus
4. Phagocytosis- cell eating

Question 14

Phagocytosis is highly conserved throughout _________

Answer 14

evolution

Question 15

Phagocytes

Answer 15

(“cell that eats”) ingest and destroy microbes by a process known as phagocytosis

Question 16

Examples of Phagocytes

Answer 16

Macrophages, Monocytes, neutrophils

Question 17

Chemotaxis

Answer 17

chasing down of microbes

Question 18

Phagocytosis

Answer 18

eating of microbes

Question 19

TRUE or FALSE

There is a variety of microbial products

Answer 19

TRUE

Question 20

In an immune response, there are shared ________ _________

Answer 20

signaling pathways

Question 21

Steps in Phagocytosis

Answer 21

1. Phagocytes detects and engages microbe
2. Microbe engagement initiates cytoskeletal rearrangements that drive phagocytosis
3. The microbe is internalized in a specialized phagosome
4. The phagosome fuses with the lysosome to form a phagolysosome
5. Lysosomal enzymes destroy ingested microbes
6. Reactive oxygen and nitrogen intermediates destroy microbial proteins, genomes and walls

Question 22

Macrophage Development

Answer 22

1. Like all blood cells, macrophages arise from undifferentiated stem cells in the bone marrow.
2. Some stem cells differentiate into short-lived monocytes that circulate in the blood.
3. Inflammation recruits monocytes to sites of infection where they differentiate into resident macrophages
4. Resident macrophages are long-lived “professional” phagocytes that ingest large amounts of extracellular material.

Question 23

Aside from eliminating microbes, what else do phagocytes do?

Answer 23

They activate neighboring cells through the release of cytokines and chemokines

Question 24

Cytokines

Answer 24

Secreted proteins that drive immune and inflammatory reactions.

In innate immunity, cytokines are produced by macrophages and natural killer cells

Question 25

One effect of cytokines

Answer 25

Induce proteins in the endothelium that make the endothelium more adherent for passing leukocytes

Question 26

Chemokines

Answer 26

A large family of structurally related, low molecular weight cytokines that stimulate leukocyte movement and regulate the migration of leukocytes from the blood to tissues

Question 27

What is the first step in innate immunity?

Answer 27

The detection of microbes by innate immune resident cells in tissue (e.g. macrophages)

Question 28

Microbe engagement triggers inflammation at the ________

Answer 28

site of infection

Question 29

resident and recruited macrophages engulf and destroy invading microbes, via ___________, and activate additional responses _____________ production

Answer 29

phagocytosis, cytokine/chemokine production