Innate Immunity

Question 1

What are the characteristics of innate immunity?

Answer 1

Fast, lack specificity, lack memory, no change in intensity = factors that prevent entry, limit growth, contain and clear infect

Question 2

What are the characteristics of adaptive immunity?

Answer 2

Slow, specific, memory, changes in intensity

Question 3

What needs to be activated for the adaptive immune response to take place?

Answer 3

Innate immunity

Question 4

What are the 4 types of barriers in innate immunity?

Answer 4

1) Physical barriers = skin, mucous mem, cilia.
2) Physiological barriers = vomiting, diarrhoea, coughing, sneezing.
3) Chemical barriers = low pH, antimicrobial molecules (IgA, lysozymes, mucus).
4) Biological barriers = normal flora.

Question 5

How can normal flora be displaced to a sterile location?

Answer 5

Breaking the skin barrier, faecal-oral route, faecal-perineal-urethral route, poor dental hygiene/dental work

Question 6

Other than displacement how can an infection take place?

Answer 6

Immune-compromised host, normal flora depleted by Abx

Question 7

Innate barriers being the first line of defence in innate immunity, what is the second?

Answer 7

Phagocytes, complement, cytokines = inflam

Question 8

What is the role of a macrophage?

Answer 8

Phagocyte, prod chemokines/cytokines, APC

Question 9

What is the role of a neutrophil?

Answer 9

60% of WBCs, increase in infect, recruited by chemokines, phagocytise pyogenic bacteria

Question 10

What is the role of a basophil?

Answer 10

Contain heparin and histamine = inflam, allergic reactions

Question 11

What is the role of an eosinophil?

Answer 11

Parasites

Question 12

What is the role of a NK cell?

Answer 12

Kill abnormal host cells

Question 13

What enables a phagocyte to recognise a microbe?

Answer 13

PAMPs (pathogen associated molecular patterns) on the microbe are recognised by PRRs (pathogen recognition receptors / toll like receptors) on the phagocyte AND/OR opsonisation

Question 14

Name some opsonins

Answer 14

Complement = C3b, Ab = IgG IgM, acute phase proteins = CRP

Question 15

What is the diff between a phagosome and a phagolysosome?

Answer 15

Phagosome = phagocytic vesicle. Phagolysosome = phagocytic vesicle fused with lysosome

Question 16

Outline a phagocytes intracellular killing mechanism

Answer 16

O2 dependent = hydrogen peroxide, hydroxyl radical, nitric oxide, oxygen radical, hypohalite.

O2-independent = lysosome, lactoferrin/transferrin

Question 17

What are the antimicrobial actions of the complement system?

Answer 17

1) C3a C5a = recruitment of phagocytes.
2) C3b-C4b = opsonisation.
3) C5-C9 = killing, MAC

Question 18

TNFα/IL-1/IL-6 from macrophages, has what actions?

Answer 18

Liver prod CRP, bone marrow cause neutrophil mobilization, vasodilation, increased vascular permeability, hypothalamus increases temp

Question 19

What reasons would cause decreased phagocytosis?

Answer 19

Decreased spleen function, decreased neutrophil count, decreased neutrophil function

Question 20

Why does losing the spleen put you at an increased risk of severe infection?

Answer 20

When the spleen is no longer present (asplenia), IgG and C3b are still bound to bacteria, but they cannot be removed from the blood circulation due to the loss of the splenic macrophages.