Innate Immunity Flashcards

1
Q

What are the differences between innate and adaptive immunity?

A

Innate - fast (secs), lacks specificity, no memory, no change in intensity
Adaptive - slow (days),specificity, immunological memory, changes in intensity

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2
Q

What are the first lines of defence within innate immunity?

A

Physical barriers
Physiological barriers
Chemical barriers
Biological barriers

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3
Q

What are physical barriers in innate immunity?

A

Skin
Mucous membranes - mouth, resp tract, etc
Bronchial cilia

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4
Q

What are physiological barriers in innate immunity?

A

Vomiting
Diarrhoea
Coughing
Sneezing

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5
Q

What are chemical barriers in innate immunity?

A

Low pH - skin (5.5), stomach (1-3), vagina (4.4)

Antimicrobial molecules - igA (saliva and tears), lysozyme, mucus

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6
Q

What are biological barriers in the innate immune system?

A

Normal flora in strategic locations - entry points

- nasopharynx, mouth/throat, skin, GI tract, vagina

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7
Q

What are the benefits of normal flora within the body?

A
  • Compete with pathogens for attachment sites and resources
  • product antimicrobial chemicals
  • synthesise vitamins - K, B12
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8
Q

What normal flora is present in the nasopharynx?

A

Streptococcus pneumoniae
Neisseria meningitidis
Haemophilus species

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9
Q

What normal flora is present on the skin?

A

Gram positive - staph aureus, staph epidermiditis, strep pyogenes

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10
Q

When might normal flora become pathological?

A
  1. Displaced from its normal location
  2. Overgrows if host immunocompromised
  3. Overgrows when normal flora depleted by antibiotics
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11
Q

Give examples of infections that may be caused from displaced microflora?

A

UTI - E.coli from the colon enters the urethra

Cellulitis - Staph.aureus enters through a break in the skin

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12
Q

Give 2 examples of infections that occur due to normal flora being depleted by antibiotics?

A

Clostridium difficile - severe colitis

Candida albicans - vaginal thrush

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13
Q

Patients may be immunocompromised if…

A
Asplenic or hyposplenic 
Diabetic
AIDS
Malignant diseases 
Chemotherapy
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14
Q

What are the second lines of defence within innate immunity?

A

Phagocytes, complement system, cytokines

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15
Q

What is the result of activation of the second line of defence?

A

Inflammation

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16
Q

What are the 3 main phagocytes in innate immunity?

A

Macrophages
Monocytes
Neutrophils

17
Q

Give examples of PAMPS on gram negative bacteria.

A

LPS

Lipoproteins and lipopeptides

18
Q

Give examples of PAMPS on gram positive bacteria.

A

Peptidoglycan

Lipoteichoic acids

19
Q

What is an example of a PRR?

A

Toll-like receptor

20
Q

What molecules act as opsonins?

A
  • Complement proteins - C3b
  • Antibodies - igG
  • Acute phase proteins - CRP, MBL (mannose-binding lectin)
21
Q

Why are asplenic patients particularly vulnerable to encapsulated bacteria?

A

These bacteria require opsonisation in order to clear, patients without a spleen have reduced opsonisation.

22
Q

Give examples of 3 encapsulated bacteria that asplenic patients are at high risk of infection with.

A

Neisseria meningitis
Strep. Pneumoniae
Haemophilus influenzae

23
Q

What are the 2 phagocyte killing mechanisms, how do they differ?

A

Oxygen-dependent pathway (respiratory burst)
= Release of toxic oxygen products - superoxide, H202, hydroxyl radicals.

Oxygen- independent pathway
= proteolytic and hydrolytic enzymes

24
Q

What are the 2 activating pathways of the complement system?

A
  1. MBL - initiated with MBL binds to mannose containing residues on proteins found on microbes
  2. Alternative - initiated by cell surface microbial constituents (endotoxins on e.coli)
25
What is the function of C3a and C5a?
Chemoattractants - recruit phagocytes
26
What is the function of C3b and C5b?
Opsonisation of pathogens
27
What is the function of C5-9?
Formation of membrane-attack complex (MAC)
28
Which cytokines are released by macrophages/monocytes?
IL-1 IL-6 TNF-alpha
29
What effects do IL-1,IL-6 and TNF-alpha have on the liver?
Synthesis and release of opsonins - CRP and MBL
30
What effects do IL-1,IL-6 and TNF-alpha have on the bone marrow?
Neutrophil mobilisation
31
How does infection result in an increased temperature?
Macrophage released IL-1, IL-6 and TNF alpha are pyrogens, and signal to the hypothalamus to increase body temperature
32
What effects do IL-1,IL-6 and TNF-alpha have on the vasculature?
Vasodilation | Vascular permeability
33
Which patients are likely to have reduced phagocytosis?
1. Decreased spleen function 2. Decreased neutrophil number - cancer chemotherapy, leukaemia/lymphoma, certain drugs (phenytoin) 3. Decreased neutrophil function
34
Which diseases are associated with decreased neutrophil function?
Chronic granulomatous disease (no respiratory burst due to defective NADPH oxidase)
35
What effect do corticosteroids have on the immune system?
Immunosuppressants