Immunity

Question 1

What are the two types of barrier immunity?

Answer 1

Physical - skin, mucus, respiratory cilia, commensal organisms

Biochemical - antimicrobial effect - sebaceous secretions in skin, lysozyme in tears, spermine in sperm, gastric acidity

Question 2

Define what is an antigen

Answer 2

Any substance capable of inducing a specific immune response

Question 3

What are the differences between innate & adaptive immunity?

Answer 3

Innate - primary line of defence, immediate response, recognise certain threats, no antigen presentation, no clonal selection, no immunological memory

Adaptive - secondary line of defence, delayed response, recognise all threats, antigen presentation, clonal selection, immunological memory

Question 4

What is the main function of neutrophils?

Answer 4

Phagocytosis (mainly innate)

Question 5

What are the types of T lymphyocytes?

Answer 5

Cytotoxic, memory, helper, suppressor

Question 6

What are the types of B lymphocytes?

Answer 6

Plasma cells, memory cells

Question 7

What is the difference between monocytes & macrophages?

Answer 7

Monocytes are when they’re in the blood.

Become macrophages when in tissue.

Question 8

What is the function of monocytes/macrophages?

Answer 8

Phagocytosis –> adaptive antigen presenting cells

Question 9

What are eosinophils for?

Answer 9

Parasitic infections & allergic responses

Question 10

What are basophils & mast cells for?

Answer 10

Inflammatory & hypersensitivity

Question 11

What is involved in innate cell-mediated immunity?

Answer 11

Phagocytes -

• Polymorphonuclear leukocytes - Neutrophils
• Mononuclear phagocyte system - monocytes/macrophages

Question 12

What is neutropenia?

Answer 12

Low neutrophil level in blood

Question 13

What is the oxidative burst in phagocytosis?

Answer 13

The process of creating the toxic chemicals used to digest the ingested microbe

Question 14

What is the role of natural killer cells in innate cell-mediated immunity?

Answer 14

Detects when cells lose MHC class I surface molecules → NK cell activation → inserts pore-forming molecules into target cell to pumps cytotoxic chemicals in

Question 15

What is involved in innate humoral immunity?

Answer 15

• Acute phase proteins (APPs) - released in inflammation/tissue injury for immediate/non-specific cytoxicity.
  E.g. CRP, pro-calcitonin, alkaline phosphatase, ferritin
• Complement - Alternative and classical pathways
  Alternative - antibody independent cell lysis
  Classical - antibody dependent cell lysis

Question 16

What are the differences between class I & II MHCs?

Answer 16

Class I - on human cells - natural antigens normal to you

Class II - on antigen presenting cells - monocytes/macrophages

Question 17

What is involved in adaptive cell-mediated immunity?

Answer 17

Antigen presented to T-cytotoxic cells.
Those that recognise the antigen replicate & differentiate.
Activated Tc cells attack the host cells presenting the Ag.
Memory Tc cells maintain immunological memory.

Question 18

What is involved in adaptive humoral immunity?

Answer 18

Antibodies - comprised to 2 heavy + 2 light chains, joined by a disulphide bond.
Heavy chains form constant region at base.
Antibody specificity determined by variable region.

Question 19

How are antibodies produced?

Answer 19

Microbes phagocytosed by APCs → present Ag to T-helper cells & stimulate B lymphocytes that recognise Ag → replicate & differentiate
B plasma cells produce antibodies that attack Ag & B memory cells to maintain immunological memory

Question 20

What is clonal selection?

Answer 20

Each B lymphocyte recognises a single Ag - specific response & memory

Question 21

What are cytokines?

Answer 21

A humoral response - control immune system.

e.g. interleukins, TNF, interferon’s, CSFs