Immunology Tutorial

Question 1

How does IgA & IgG protect against viral infection?

Answer 1

• Neutralising antibodies (fab domain) - prevent adhesion of virus to human cell
• IgG can induce antibody dependent cellular cytotoxicity (ADCC)
• Fcy Receptor III/CD16 on NK cells bind IgG

Question 2

Describe the distribution of antibodies

Answer 2

• IgM - plasma
• IgG - plasma + tissues - enters fetus through placenta
• IgA - mucosal surfaces - breast milk
• IgE - mast cells

Question 3

Describe the immune response to intracellular bacteria

Answer 3

1) TH cell recognises peptides presented on MHC2 > secretes cytokines (IFNy) to help macrophage kill
2) Mucosal immune response > prevention of adhesion > IgA secreted, neutralising antibodies directed at virulence factors. IgA production requires class switching with help of TH1 cells.
3) Phagocytosis of extracellular pathogens - most efficient when bacteria opsonised with C3b + IgG, recruitment of neutrophil induced by IL17 by TH17 cells

Question 4

What does the induction of AID enzyme lead to?

Answer 4

• Class switching = IgA, IgG or IgE
• Affinity maturation
• Plasma cells producing IgG, IgA or IgE (IgG = most effective at phagocytosis, great at neutralisation)
• Memory cell

Question 5

What do adjuvants in vaccines do?

Answer 5

Those with TLR ligands stimulate CD40 expression + B7

Question 6

What is a conjugate vaccine?

Answer 6

Linked recognition e.g. conjugate vaccine

• Solution = covalently bind polysaccharide to protein
• Polysaccharide recognised + internalised
• Protein degraded + presented to T cell
• T cell stimulates class switch = anti-polysaccharide IgG

Overall: Combines weak antigen (e.g. polysaccharide) with strong antigen as carrier so immune system has stronger response to weak antigen

Question 7

What is the disease progression for whooping cough (bordetella pertusis)?

Answer 7

1) Runny noise, low grade fever, mild occasional cough
2) Irritating cough, characteristic whoop accompanied by vomiting + exhaustion, periods of apnoea
3) Susceptible to other resp infections, gradual recovery, coughing lessons but fits may return

Question 8

What are the functions of different CD4 T cells?

Answer 8

TH1 - helps macrophages suppress IC infections
TH2 - helps basophils, mast cells, eosinophils + B cells respond to parasitic infections
TFH - helps B cells become activated, switch isotype + increase antibody affinity
TH17 - enhance neutrophil response to fungal + EC bacterial infections
Treg - suppress activities of other effector T cell populations

Question 9

What are the symptoms of Mumps?

Answer 9

• Early: fever, malaise, headache, anorexia, photophobia, earache
• Late: swelling salivary glands, parotid glands, hearing loss, testicular swelling, oophoritis
• Complications: encephalitis, meningitis, parotitis, permanent deafness

Question 10

What happens in somatic hypermutation of Ig V regions?

Answer 10

= point mutation introduced into V region of immunoglobulin genes
- some substitutions in antigen binding site will increase affinity of Ig for binding to antigen

Question 11

Which HPV types cause genital warts?

Answer 11

6, 11

Question 12

Which HPV types cause cancer?

Answer 12

16, 18

Question 13

What is IgM great at?

Answer 13

Activating complement

Question 14

What are the types of memory T cells?

Answer 14

1) Central memory cells - express CCR7

2) Effector memory cells - don’t express CCR7