Innate Immunity

Question 1

What are 4 key characteristics that differentiates the innate from the adaptive immune system?

Answer 1

1. Reacts to a limited number of molecules
2. Can’t adapt
3. Rapid response
4. No memory (no long lasting protection)

Question 2

Give 2 examples of internal and external barriers that the innate IS uses to protect against infection?

Answer 2

Internal - inflammatory response, physiological barriers

External - Skin, mucous membranes, GI tract, sinuses

Question 3

How does the skin protect the body from infection?

Answer 3

Has two layers - dermis and epidermis.

Outer layer of the epidermis consists of dead cells filled with keratin (impermeable to pathogens) and is shed every 10-15 days which gets rid of the bacteria, etc. on the skin surface.

Dermis has sebaceous and sweat glands - sebaceous glands produce sebum (pH 3-5) to provide undesirable environment for replication/growth.

Question 4

What kind of physiological barriers does the body have?

Answer 4

• temperature -> rises (fever) to prevent replication
• pH -> especially gastric acidity for ingested pathogens
• Soluble factors -> lysozyme cleaves polypeptides, complement

Question 5

Name 3 cell types in the innate IS and their lineage.

Answer 5

Myeloid lineage:

• Neutrophils
• Basophils
• Eosinophils
• Mast cells
• Monocyte/Macrophage

Lymphoid lineage:
- NK cells

Question 6

Where do B and T cells mature?

Answer 6

B cells - Bone marrow

T cells - Thymus

Question 7

How do NK cells differentiate infected cells from non-infected cells?

Answer 7

Cells present proteins to outside of cell (MHC I) which inhibit apoptosis. If these are not expressed, it is likely due to interferon production within the cell which is suppressing protein synthesis. As a result, inhibitory proteins cannot be expressed/presented and the cell dies.

Question 8

What recognition systems can be used to identify affected cells?

Answer 8

Direct:
- PAMPs (pathogen-associated molecular patterns)
- PRRs (pattern-recognition receptors)
Tagging & receptors
- Use opsonins (eg C3b or antibody) to tag cells to be recognised by receptors (C3bR or FcR)

Question 9

What are 5 signs that an inflammatory response is taking place?

Answer 9

• Rubor (redness)
• Tumor (swelling)
• Calor (heat)
• Dolor (pain)
• Functio laesa (loss of function)

Question 10

What are the major events of the inflammatory response?

Answer 10

1. Vasodilation (redness & heat)
2. Increased capillary permeability (swelling & pain)
   
   • influx of liquid, increased protein conc
3. Increased number of phagocytic cells (pain & loss of function)

Question 11

What type of inflammation occurs when tissue damage occurs?

Answer 11

Sterile inflammation

Question 12

What important molecule do mast cells release?

Answer 12

Histamine! :D