Innate Immunity

Question 1

What is the main function of Natural Killer cells?

Answer 1

Killing infected cells and inducing apoptosis in viral infected and tumor cells

Natural Killer cells play a crucial role in the innate immune response.

Question 2

What are the components released by Natural Killer cells to induce apoptosis?

Answer 2

Perforin and granzyme

These cytoplasmic granules are essential for the function of Natural Killer cells.

Question 3

What does the innate immune system serve as?

Answer 3

The first line of defense and is non-specific

It includes physical and chemical barriers that protect the body.

Question 4

Name three physical barriers involved in innate immunity.

Answer 4

• Skin
• Mucus
• Stomach acid

Question 5

What are the three pathways of the complement system?

Answer 5

• Classical
• Alternative
• Mannose-binding lectin (MBL)

Question 6

What is phagocytosis?

Answer 6

Ingestion of foreign material

It is a critical process in the innate immune response.

Question 7

What is the role of NADPH oxidase in phagocytosis?

Answer 7

Produces superoxide for the respiratory burst

This reaction helps to kill ingested pathogens.

Question 8

What are acute phase proteins?

Answer 8

Plasma proteins produced in response to injury, inflammation, or infection

Examples include C-reactive protein (CRP).

Question 9

True or False: The innate immune response has memory.

Answer 9

False

The innate immune response does not have lasting protective immunity.

Question 10

What does the term ‘immunity’ refer to?

Answer 10

Collective term for the protection of the body from disease

It encompasses both innate and adaptive immune responses.

Question 11

What are the two main types of adaptive immunity?

Answer 11

• B-cell immunity (humoral immunity)
• T-cell immunity (cell-mediated)

Question 12

Fill in the blank: _______ are molecules that bind foreign substrates making them more susceptible to phagocytosis.

Answer 12

Opsonins

Question 13

What are monocytes and how do they relate to macrophages?

Answer 13

Monocytes are mononuclear phagocytic leukocytes that mature into macrophages after circulating for ~8 hours

Macrophages are larger and more phagocytic than monocytes.

Question 14

What is the function of C3b in the complement system?

Answer 14

Opsonisation of bacteria

It enhances the phagocytosis of pathogens.

Question 15

What triggers the classical complement pathway?

Answer 15

Binding of C1 to an antigen-antibody complex

This activation leads to a cascade resulting in pathogen lysis.

Question 16

What is the role of the membrane attack complex (MAC) in innate immunity?

Answer 16

Lysis of pathogens, particularly Gram-negative bacteria

MAC forms pores in the membranes of target cells.

Question 17

What is the primary defense system of innate immunity?

Answer 17

Physical and chemical barriers, acute phase proteins, complement, and phagocytes

These components work together to protect the body from pathogens.

Question 18

What are the key characteristics of the innate immune response?

Answer 18

• First line of defense
• Non-specific
• Present from birth
• No memory or lasting protective immunity