Ige Response To An Allergen

Front 1

What does the first encounter with an allergen involve?

Back 1

- APC digests allergen and presents fragments to T-helper cell which proliferates excessively
- B cells stimulated to produce plasma cells that excessively generate IgE antibodies
- IgE antibodies containing histamine attach to mast cells and basophils in the body

Front 2

What will subsequent encounters with the same allergen involve?

Back 2

- Allergen combines with IgE on mast cells and basophils once it re-enters the body
- This triggers mast cells and basophils EVERYWHERE to release inflammatory chemicals (degranulation) including histamine; inflammatory response takes only seconds and lasts up to 30mins

Front 3

What are the local responses that histamine causes in an IgE response?

Back 3

Runny nose (increased mucus)
Watery eyes (increased tears)
Reddened skin (localised)
Blood vessel dilation (leakage & oedema)

Front 4

What are the systemic responses that histamine causes in an IgE response?

Back 4

Smooth muscles contract (bronchioles = asthma)
Swelling of tongue/lips
Sudden vasodilation = anaphylactic shock

Front 5

Effects of histamine

Back 5

Systemic vasodilation
Increased vessel permeability
Decreased myocardial contractility
Decreased coronary blood flow
Dysrhythmias
Bronchoconstriction
Pulmonary vasoconstriction

Front 6

How is respiration compromised during anaphylactic shock?

Back 6

SOB/wheezing/stridor/cough - from swelling, bronchoconstriction and increased mucus secretion

Front 7

What causes abdominal cramps and diarrhoea?

Back 7

Inflammation; once a route is sensitised it's inflammation allows antigens to spread throughout the body more easily

Front 8

What do vasodilation and increased permeability cause in anaphylaxis?

Back 8

Swelling, redness, hives (urticaria) from extracellular fluid accumulation
Laryngeal oedema (swelling in and around neck)
Fainting - from the resulting sharp decrease in BP Hypotension