Immunology

Question 1

Stimulation of the immune system by viruses and bacteria would protect or defect against developing allergies

Answer 1

Protect.

Question 2

What cell is mostly responsible for allergies?

Answer 2

T-helper2

Question 3

What might protect against the Th2 phenotype?

Answer 3

Having older siblings

Living on a farm

Frequent helminth infections

Question 4

What are the steps of the anaphylactic reaction to an allergen? (5)

Answer 4

Allergen recognition
Antigen presentation 
Activation of CD4+ve Th2 cells 
Th2 interact with B cells
Mast cell degranulation

Question 5

What happens in antigen recognition and presentation in response to an allergen?

Answer 5

Allergen has to gain access to the tissues or a dendritic cell must sample to airway environment. In respiratory viral infections a loss in the epithelial layer can occur.

Question 6

What are dendritic cells?

Answer 6

APC cells that recognise and engulf non-self and present it to the immune system in conjunction with the MHC II

Question 7

How are CD4+ Th2 cells activated by dendritic cells?

Answer 7

1. The MHCII with antigen is presented to the TCR on the T-cell.
2. A co-stimulatory signal is produced from the interaction of CD80/86 on the Dendritic cell with CD28.

Question 8

How do Th₂ cells then activate B cells in response to an allergen?

Answer 8

The Th2 cell presents the antigen fragment to the B cells and the Th2 cell cytokine IL-4 and IL-13 promote the lass switch to IgE

Question 9

What is FcℇRI and it’s interaction with IgE?

Answer 9

Expressed only on mast cells as the receptor for IgE, it binds with extremely high affinity.

Question 10

Actions of histamine?

Answer 10

Opening of capillary bed to increase blood flow to the affected area

Pain/itch

Smooth muscle constriction

Leucocyte recruitment to the area

Question 11

Consequences of allergen exposure?

Answer 11

Eyes get itchy, red and watery

Nose - sneezing running and itch.

Airways - chest tightness

GI tract - Cramp, Diarrhoea

Question 12

What lipid mediator is a potent bronchoconstrictor

Answer 12

CysLt, which is a leukotriene.

Question 13

What anatomical changes cause bronchoconstriction when exposed by an allergen?

Answer 13

Initially contraction of bronchial smooth muscle

After 30mins it is the airway lumen.

Question 14

What’s the difference in an allergy and asthma?

Answer 14

In an allergy it is the release of mast cell mediators.

Question 15

What causes a second wave of smooth muscle constriction?

Answer 15

Eosinophils by releasing mediators such as CysLT, eosinophil granules are also toxic to epithelial cells and stimulate mucus production.

Question 16

What are the histological changes of the asthmatic lung?

Answer 16

Increased mucus production

Thickening of lamina reticularis

Hypertrophy and hyperplasia of the bronchial smooth muscle

Question 17

Common viruses causing a cold?

Answer 17

Rhinovirus 30-35%, coronavirus 10%, flu virus

Question 18

Common causes for a sore throat?

Answer 18

Cold viruses cause about 40%

Bacteria cause about 15%

Question 19

What is RSV?

Answer 19

Respiratory syncytial virus

Can cause bronchiolitis in children.

Antibodies are not very effective

Question 20

Associated complications of RSV and treatments?

Answer 20

Otitis media, Tracheo-bronchitis with prolonged cough.

Most cases just require hydration and symptomatic relief
Ribavirin to those at sever risk.

Question 21

Structure of the influenza virus?

Answer 21

RNA virus with a genome consisting of 8 units

Enveloped and consists of three different types.

Question 22

Complications of influenza virus?

Answer 22

Exacerbation of chronic underlying issues.

Pneumonia

Rye’s syndrome

Question 23

What are the two types of antigen on the flu viruses envelope?

Answer 23

haemagglutinin

neuraminidase

Question 24

Difference in influence A/B and then C?

Answer 24

A and B both undergo antigenic shifts (‘mutates’)

Question 25

What is antigenic drift?

Answer 25

The gradual accumulation of mutations

Question 26

What is the function of haemagglutin?

Answer 26

Binds the virus to target epithelia, fuses the membrane of the cell.