Extracellular immunity I

Question 1

Extracellular prokaryotes

Answer 1

• E.coli
• Strep pyogenes
• Clostridium tetani
• Staph aureus
• Helicobacter pylori

Question 2

Fungi

Answer 2

Candida albicans

Question 3

Parasites

Answer 3

• Trypanosoma brucei

- Schistosomiasis

Question 4

QALYS and DALYS

Answer 4

QALYs (Quality-Adjusted Life Year) and DALYs (Disability-Adjusted Life Year) are common terms used within this framework. QALYs are a measure of years lived in perfect health gained whereas DALYs are a measure of years in perfect health lost. They are the most frequently cited metrics for risk-benefit assessment

Question 5

Barrier defenses to extracellular infection

Answer 5

Skin, gut, eyes, lungs

Epithelial cells, cilia, low ph in the gut, lysozyme in the eyes and gut normal flora

Question 6

Pemphigus

Answer 6

Caused by an antibody against desmin and destroys tight junctions

Question 7

Primary cilia dyskinesia

Answer 7

Heart on the wrong side

Question 8

Soluble mediators

Answer 8

• Ficolins
• Lysozyme - N acetyl muramide glycan hydrolase - gram positive cell wall
• Lactoferrin - iron chelator - sequesters nutrients
• Defensins, cathelicidins, Reg III (AMPs)
• Innate antibodies in gut
• Phospholipase A2
• Complement
• Collectins - MBL, surfactant

Question 9

Th2 response

Answer 9

Caused by DCs leading to IL-4, IL-5 and IL-13 production

GATA-3 transcription factor important in leading to the response

Question 10

Antibody response

Answer 10

Make IgA/IgG/IgE

Class switching of IgA1 to IgA2

Question 11

Th2 mediators also activate non B cells

Answer 11

• Il-5 leads to increased eosinophils
• Il-9 leads to increased basophils
• IgE binds to basophils and mast cells - produce histamine

Question 12

Th17 response in extracellular infection

Answer 12

Driven by IL-23, TGF-B, IL-6 and RORy
Mediated by neutrophils
proinflammatory - IL-1, IL-6, IL-8
antiinflammatory - IL-4, IL-10

Question 13

Strep pyogenes - virulence and evasion of the response

Answer 13

• has bacterial adhesins and invasins
• complex capsules
• surface M proteins inactivate C3b
• secrete C5a protease, CD11b homologue
• Streptolysins
• Protein G

Question 14

Toxic shock

Answer 14

Superantigen triggers T cells non specifically so any T cell becomes activated leading to a cytokine storm and multiple organ failure

Question 15

E.coli O157:H7

Answer 15

Uropathogenic E.coli obtained adhesins leading to haemorrhagic diarrhoea

Question 16

Endotoxic shock from E.coli

Answer 16

Leads to:

• inflammatory damage
• NF-kB
• TNF-a, IL-1, IL-8
• Coagulation, ox and nitric free radicals etc

Question 17

Helicobacter pylori

Answer 17

Gram negative, causes stomach ulcers and cancer
80% of carriers are asymptomatic
Outer membrane includes putative adhesins, Fe2+ transporters, flagella proteins
Express catalase and urease
CapPAI (40 genes) make it pathogenic - the genes include superoxide dismutase which is involved in Type IV secretion

Question 18

Fungal infection

Answer 18

• Tinea corpis - ring worm
• Malassezia furfur - dandruff
• Aspergillus fumagatus - asthma

Question 19

Fungal recognition

Answer 19

Dectin -1 is a receptor that binds to glucans and skews the immune response to a TH17

Question 20

Defects in fungal immunity

Answer 20

Neutropenic patients and individuals with mutations (promoter polymorphisms) in Dectin-1 - C.albicans

Chronic Granuloma Disease patients - Aspergillus
- defects in producing ROSs

AIDS - p. jirovecii