Hypersensitivity #2

Question 1

How to diagnose allergies?

Answer 1

skin tests - introduce small quantity of allergen into skin and check for swelling/redness from local mast cell degranulation

Question 2

How can allergies be treated?

Answer 2

~ hyposensitisation - increases IgE response to allergens = inhibits IgE activity
~ infect patient with tapeworm - immune system focuses on fighting worm infection and not allergens

Question 3

Hyposensitisation

Answer 3

~ administer small repeated low/increasing doses of allergen
EFFECTS:
1) tolerance via immunosuppressive cytokines (TGF-beta + IL-10) inducing T(REG) cells
2) generation of IgG4 antibodies that compete with IgE or reduce FCERI signalling by co-clustering with inhibitory FcyRII receptors

Question 4

Chronic type 1 hypersensitivity

Answer 4

~ type 1 h. can sometimes develop into chronic form
~ characterised by extravasation of basophils –> stimulate fibroblasts –> release chemokines –> other granulocytes attracted –> chronic inflammation

Question 5

When does HR type II occur?

Answer 5

~ blood transfusions
~ haemolytic disease of newborn
~ haemolytic anaemia

Question 6

Haemolytic disease of newborn

Answer 6

~ cause by reaction to a diff, blood group antigen = Rhesus (Rh) antigen
~ occurs if pregnant mother is Rh- and child is Rh+
~ exposure to umbilical cord blood during birth on 1st pregnancy produces antibodies to Rh antigen which cross the placenta in 2nd pregnancies

Question 7

Haemolytic anaemia

Answer 7

~ when certain antibiotics non-specifically bind to the surface of erythrocytes and are perceived as foreign antigens
~ antibodies produced that result in haemolytic if the drug administration is continued
e.g. penicillin, streptomycin

Question 8

Blood group antigens

Answer 8

~ everyone expresses H antigen
~ group A express A, B - B, AB - A & B, O - neither
~ people develop antibodies against any blood group antigen they do not express themselves
~ antigens are carbohydrates and similar to those found on gut bacteria

Question 9

What infections can cause HR type III?

Answer 9

~ meningitis
~ hepatitis
~ malaria
~ trypanosomiasis

Question 10

Which pathogens can cause HR type IV?

Answer 10

~ measles (virus)
~ Listeria (bacteria)
~ Leishmania (protozoan)

Question 11

Name 2 example of HR type IV.

Answer 11

~ contact dermatitis (poise ivy)

~ tuberculin reaction (test for exposure to TB)

Question 12

Chronic inflammation

Answer 12

pathological condition characterised by persistent, increased expression of inflammatory cytokines due to the immune system not being turned off properly

Question 13

Name the origins of chronic inflammation.

Answer 13

~ infection
~ not fully-resolved infection
~ non-infectious (obesity = most common cause)

Question 14

Cytokines produced during chronic inflammation can cause…

Answer 14

~ tissue scaring (organ dysfunction)
~ cell proliferation
~ angiogenesis (tumour development)

Question 15

Consequences of the obesity epidemic.

Answer 15

~ adipocytes can be stimulated to produce inflammatory cytokines
~ CI increases susceptibility to systemic diseases (incl. diabetes II)
~ inflammatory cytokines (assoc. w/ CI) contribute to insulin resistance by interfering w/ signalling enzymes downstream of insulin receptor

Question 16

Adipocytes

Answer 16

visceral fat cells

Question 17

Consequences of diabetes.

Answer 17

~ loss of glucose homeostasis
~ retinopathy
~ kidney failure
~ cardiovascular disease