HD16 Allergic Diseases

Question 1

What are the allergic response symptoms that you may see that are sever and potentially lifethreatening?
2) What should you do after dealing with the crisis?

Answer 1

1) breathing difficulties, swelling and itching, urticaria/ hives, incontinance, diarrhoea, cramps
2) refer to appropriate specialists for further investigation

Question 2

What is hypersensitivity?

Answer 2

Immune mediated antigen-specific reaction that are inappropriate or excessive and result in harm to the host.

Question 3

What 2 ways can hypersensitivity be mediated?

Answer 3

Antibody mediated

T cell mediated

Question 4

What 3 things can hypersensitivity be against?

Answer 4

Environmental agents
Self antigens
Infectious agents e.g. hep B, leprosy (tuberculoid reactions)

Question 5

Whats the other name of a type 1 hypersensitivity?

Answer 5

immediate mediated (IgE)

Question 6

Whats the other name of a type 2 hypersensitivity?

Answer 6

antibody mediated

Question 7

Whats the other name of a type 3 hypersensitivity?

Answer 7

immune complex mediated

Question 8

Whats the other name of a type 4 hypersensitivity?

Answer 8

T cell mediated (delayed)

Question 9

Whats the other name of a T cell mediated hypersensitivity?

Answer 9

type 4

Question 10

Whats the other name of a immune complex mediated hypersensitivity?

Answer 10

type 3

Question 11

Whats the other name of a antibody mediated mediated hypersensitivity?

Answer 11

type 2

Question 12

Whats the other name of a immediate mediated hypersensitivity?

Answer 12

type 1

Question 13

What type of antibody is involved in type 1 hypersensitivity?

Answer 13

IgE

Question 14

What antibodies are involved in type 2 hypersensitivity?

Answer 14

IgM , IgG

Question 15

What antibodies are involved in type 3 hypersensitivity reactions?
2) Anything else involved?

Answer 15

1) IgM and IgG

2) extracellular matrix antigens

Question 16

what is involved in type 4 hypersensitivities?

Answer 16

CD4 + T cells (delayed- type hypersentivity)

CD8+ CTLs (T cell mediated cytolysis)

Question 17

Describe the mechanisms of tissue injury and disease through type 1 hypersensitivity?

Answer 17

mast cells and their mediators (vasoactive amines, lipid mediators and cytokines)

Question 18

Describe the mechanisms of tissue injury and disease through type 2 hypersensitivity?

Answer 18

so the antibody binds to an intrinsic (self) or extrinsic (come from pencillin or virus) antigen on a host cell e.g. RBC=

1) opsonisation and phagocytosis of cells
2) complement and Fc receptor mediated recruitment and activation of leukocytes (neutrophils, macrophages)
3) abnormalities in cellular functions e.g. hormone receptor signalling

Question 19

Describe the mechanisms of tissue injury and disease through type 3 hypersensitivity?

Answer 19

complement and Fc receptor mediated recruitment and activation of leukocytes
(this one is similiar to type 2, but misses out a few of the responses due to not involving extracellular matrix antigens)

Question 20

Describe the mechanisms of tissue injury and disease through type 4hypersensitivity?

Answer 20

1. CD4+ T cell= macrophage activation, cytokine-mediated inflammation
   2, CD8+ CTLs = direct target cell killing, cytokine mediated inflammation

Question 21

What is the hygiene hypothesis

Answer 21

Decreased infection
Increased immunisation
Leads to preferential switch from type 1 profile to type 2 profile

Question 22

What is atopy?

Answer 22

Atopy refers to the genetic tendency to develop allergic diseases such as allergic rhinitis, asthma and atopic dermatitis (eczema)

Question 23

In type 1 hypersensitivity. IgE mediated degranulation of mast cells and basophils.
What is released?

Answer 23

Release of histamine, heparin, lysosomal enzymes and proteases

Question 24

What are the clinical consequences caused by increased cappillary permeability with hypersensitivity reactions?

Answer 24

Tissue oedema, urticaria, itching, rhinitis
Laryngeal oedema: (Airway obstruction,,
Respiratory distress
Stridor)
Fluid leakage from vascular space (Hypovolemic shock)

Question 25

What are the clinical consequences caused by smooth muscle contraction with hypersensitivity reactions?

Answer 25

Bronchospasm: (Respiratory distress, cough) GI tract spasm: (Nausea, vomiting & Cramps, diarrhoea) Bladder spasm (Urinary urgency/incontinence)

Question 26

What investigations are undertaken to diagnosis hypersensitivity to a particular antigen?

Answer 26

1. skin prick tests 2. blood tests (specific IgE) 3. challenge tests (to overcome false positives and negative results: could be given oral/iv (double blind placebo controlled)

Question 27

What is the definition of anaphylaxis?

Answer 27

Severe allergic reaction with 1 or both of:- Breathing difficulties hypotension

Question 28

What do u if a patient is in anaphylaxis, (especially if skin changes are present)

Answer 28

oxygen

Question 29

following anaphylaxis and treatment with oxygen, what would you do if this then occured: Stridor, wheeze, respiratory distress or clinical signs of shock

Answer 29

Adrenaline 1:1000 2,3 solution; 0.5ml (0.5mg) intramuscular

Question 30

patient has anaphylaxis, oxygen administered then , wheezing occurs then Adrenaline 1:1000 2,3 solution; 0.5ml (0.5mg) administered intramuscularly: 2) what do you do if this doesn't help?

Answer 30

Repeat asministering adrenaline in 5 mins if no clinical improvement 2) Antihistamine (chlorpheniramine) 10-20mg IM or slow IV

Question 31

For all severe or recurrent reactions and patients with asthma give ...........

Answer 31

For all severe or recurrent reactions and patients with asthma give hydrocortisone 100-500mg IM or slow IV

Question 32

If clinical manifestations of shock do not respond to drug treatment give .....

Answer 32

1-2L of fluid IV4. Rapid infusion or one repeat dose may be necessary.

Question 33

What are the 3 things used to treat type 1 reactions?

Answer 33

antihistamines e.g. Cetirizine steroids e.g. Prednisolone, hydrocortisone bronchodilators e.g. salbutamol