IMMUN: Infection + Immunity

Question 1

cytokine storm

Answer 1

• occurs during severe COVID
• lots of pro-inflammatory cytokines
• overactive immune system > weakened and susceptible to superinfection
• more tissue damage (producing PAMPs and DAMPs) results in greater cytokine secretion + inflammation

Question 2

how to treat severe covid

Answer 2

• immunotherapy: convalescent (recovering Pt) plasma transfusion
• neutrophils and macrophages are activated > swelling in lung tissue
• give IgA which is found in mucosa like covid > blocks and neutralises virus

Question 3

“long covid”

Answer 3

• health problems caused by COVID but have a later onset

Question 4

4 types of hypersensitivities

Answer 4

• type 1: immediate e.g. allergy, anaphylaxis (CANNOT have PAMPs or DAMPs)
• type 2: antibody mediated e.g. Graves disease
• type 3: immune complex mediated e.g. poststreptococcal glomerulonephritis
• type 4: T cell mediated e.g. T1D and RA

Question 5

2 types of cells involved in allergy

Answer 5

• mast cells: granules contain histamines, prostaglandins, heparin
• basophils: granules contain histamines and cytokines (IL-4 and IL-13)
• both IgE-mediated inflammation

Question 6

sensitisation (first step in allergy)

Answer 6

• allergen enters body and is phagocytosed (if skin > langerhans cell or if elsewhere, dendritic cells)
• presented to naïve Th cell on MHC II marker> TH2 cell secretes IL-4
• B cells differentiate into plasma cells > secrete IgE (class switching due to IL-4) which binds to mast cell and basophils from Fc region

Question 7

allergic response (second step)

Answer 7

• upon secondary exposure to allergen, allergen binds to IgE on mast cells > crosslinks
• leads to degranulation and release of histamine > allergic response
• 2 phases: immediate reaction phase using preformed chemical mediators (histamine) or late reaction phase using new chemical mediators (phospholipids, arachidonic acid, cytokines, prostaglandins)

Question 8

effects of histamine

Answer 8

• vasodilation
• leaky capillaries
• smooth muscle constriction
• oedema

Question 9

allergy immunotherapy

Answer 9

• allergen extract in tablet form
• administered sublingually
• takes years to develop immunity
• decreases mast cell and basophil activity and hence release of inflammatory mediators > prevent anaphylaxis

Question 10

what can immunotherapy be used for

Answer 10

• immunodeficiencies
• autoimmune diseases
• transplant rejections

Question 11

how do cancer cells evade detection

Answer 11

• stop expressing MHC I markers so CD8 (Tc) cells don’t recognise them
• express normal self antigens on MHC I so they blend in
• express ‘brake’ molecules that stop co-stimulation (signal 2) of T cells > anti-CTLA-4 or anti-PD-1

Question 12

‘brake’ molecules

Answer 12

• PD-1 binds to PD-L1 on T cell > T cell apoptosis > immunotherapy is anti-PD-1
• CTLA-4 binds to CD80/86 on APC > turns off T cells > immunotherapy is anti-CTLA-1

Question 13

3 types of immune control in a virus

Answer 13

• no control
• viral clearance
• viral persistance

Question 14

which cell doesn’t have PD-L1

Answer 14

• neutrophils

Question 15

the outcome of some viral infections can be transformation. what does this mean?

Answer 15

• virus has turned host cells into tumour cells

Question 16

monoclonal antibodies to treat systemic lupus erythematosus are specific for what?

Answer 16

BAFF