Intro to Immunity

Question 1

What are the components of the immune system?

Answer 1

1. Primary lymph organs
   - BM
   - Thymus
2. Secondary lymph organs
   - Lymph nodes
   - Adenoids
   - Tonsils
   - Spleen
   - Appendix
   - Peyer’s patches
3. Circulatory and Lymphatic systems

Question 2

What are the 3 tiers of host defense?

Answer 2

1. Barrier Immunity
   - Skin, Eyes, RT, GIT, GUT
2. Innate Immunity
   - Immediate response to breach of barriers
   - Innate immune cells
3. Adaptive immune response
   - Adaptive immune cells
   - Antibodies

Question 3

Barrier features of skin?

Answer 3

• physical
• Commensal microbes
• Sweat

Question 4

Barrier features of RT?

Answer 4

• Nasal hairs and mucus
• Cilia
• Lysozyme
• Sneeze and cough reflex
• Commensal microbes

Question 5

Barrier features of the eyes?

Answer 5

• Eyebrows and eyelashes
• Lysozyme in tears
• Blink reflex

Question 6

Barrier features of the GIT?

Answer 6

• Physical
• Peristalsis
• Vomiting and diarrhoea
• Gastric acid
• Commensal flora in SI
• Antimicrobial peptides from epithelial and immune cells

Question 7

Barrier of the GUT?

Answer 7

• Flow of urine
• Lysozyme in bladder
• Commensals in Vagina
• Low pH in Vagina

Question 8

What are PAMP’s?

Answer 8

Pathogen Associated Molecular Pattern

• Anything on/in a pathogen that the immune system recognises as non-self.
• Recognised by PRR’s. (Pattern Recognition Receptor)

Question 9

Where are PRR’s found?

Answer 9

• Cell surface
• Cytosol
• Endosome

Question 10

Function of Neutrophils?

Answer 10

• Most abundant immune cell in blood
• Phagocytosis
• Degranulation
• NET’s
• Good against Bacteria (also fungi and viruses)

Question 11

Function of Eosinophils?

Answer 11

• Degranulation
• Good against parasites
• Involved in allergic reactions

Question 12

Function of Basophils

Answer 12

• Produce histamine
• Cause inflammation
• Involved in allergic reactions

Question 13

Function of Mast Cells?

Answer 13

• Produce histamine
• Cause inflammation
• Involved in allergic reactions

Question 14

Function of Monocytes?

Answer 14

• Replenish Macrophages and DC’s when needed
• APC
• Phagocytosis
• Cytokine production
• 50% in spleen
• Involved in all infections

Question 15

Function of Macrophages?

Answer 15

• Phagocytosis
• APC
• Cytokine and chemokine production
• Involved in all infections

Question 16

Function of DC’S?

Answer 16

• Phagocytosis
• APC (Travel to LN’s)
• Involved in all types of infections

Question 17

Function of Natural killer cells?

Answer 17

• Perforin and proteases

- Create pores in target=> Cell death

Question 18

Describe antigen presentation to T Cells.

Answer 18

1. Dendritic cell becomes APC
2. Goes to LN
3. Presents to naïve T cell
4. T cell becomes activated/effector T cells
5. Produce cytokines
6. Producing T helper cells
7. Activation of other immune cells e.g B cells into plasma cells
8. Destroy pathogen

Question 19

Types of T cells?

Answer 19

T Helper cells

• CD4+
• Help enhance phagocytosis in macrophages (Th1)
• Help cytotoxic T cells (Th1)
• Help B cells make antibodies (Th2)
• Regulatory (Treg)
• Enhance neutrophil prod and recruitment (Th17)

Cytotoxic T cells

• CD8+
• Kill infected or altered cell

Question 20

Function of B Cells?

Answer 20

Become plasma cells

- Produce antibodies

Question 21

Function of Antibodies?

Answer 21

1. Neutralisation
2. Opsonisation
3. Complement activation