Immunology

Question 1

4 Cardinal signs of inflammation
pathogenesis

Answer 1

Inflammatory mediators incl hormones like:
bradykinin and histamine induce vasodilation
Bradykinin increases capillary permeability

1. Redness (erythema)
   Dilation of blood vessels causes more blood to flow to region, become more visible
   [Leaking of plasma and plasma proteins into interstitial fluid through the more permeable blood vessels also causes blood to become more viscous and slow-flowing, and the accumulation of blood in the area causes redness. ]
2. Heat
   Increased blood flow to region brings greater volume of water
   Water has high heat capacity
3. Swelling (oedema)
   Increased permeability of blood vessels causes blood plasma to leak into the interstitial fluid between cells, leading to accumulation of fluid in tissues and thus swelling.
4. Pain
   Prostagladin stimulate and irritate nerve endings, causing pain
   Has a protective function - makes individual protect the area

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5. Loss of function

Question 2

Process of allergic reaction

Answer 2

Sensitisation (no symptoms)
Dendritic cells, antigen-presenting cells are exposed to allergen, recognise and phagocytose it
Processes antigen and presents it on MHC to T helper cell
T helper cell activates and releases cytokines (IL-2, IL-4, IL-13) which activate B cells
B cells undergo rapid clonal expansion, differentiating into plasma B cells and memory B cells.
IgE produced by mast cells
IgE binds to and coats surface of mast cells

Subsequent exposure
Allergen binds to the antigen-specifc IgE coating mast cell surfaces
Causes IgE to cross-link, leading to mast cell degranulation
Releases histamine which causes inflammation

> Mast cell degranulation is usually localised.
If systemic, it causes an anaphylactic reaction.

Atopy = the genetic tendency to develop allergic reactions

Question 3

Innate vs adaptive immunity

Answer 3

innate vs adaptive
presence - constitutively present in body vs Activated upon intrusion of pathogen
specificity- no vs Specific to antigen of pathogen
Response time- rapid vs Slow (1-2weeks)
memory- no vs yes
Allergic reaction- none vs Immediate and delayed hypersensitivity