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Hypersensitivity

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by

Yara Lackousha

on 29 April 2015

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Transcript of Hypersensitivity

Let's
stop and
reflect
What's hypersensitivity?
Body reacts with exaggerated immune response to what is perceived as foreign substance.
Antigen – Antibody reaction
But, how does an
allergic
reaction
occur?
Types of Hypersensitivity
Type 1
Allergen
is a substance often harmless that a body recognize as a pathogen or a harmful invader which evokes immune responses (fever, inflammations, rash… etc)
Hypersensitivity
Allergen
2nd encounter
Th2
IgE on the surface of mast cell causes degranulation of the mast cell releasing chemicals as Histamine therefore resulting in allergic responses like inflammation and swelling

Stimulates B cells to
produce IgE
Eating something you are allergic to can cause nausea and vomiting
Skin rash, hives, itching, blisters, or skin peeling.
Symptoms
Stuffy nose, itchy nose and throat, and cough
Eyes may cause itchy, watery, red, swollen eyes
Type 2
Type 3
Type 4
Type I Hypersensitivity
Classic Allergy

Common Allergens for type 1 Hypersensitivity
Dust mite
Plant Pollens
Certain food
Drugs as Penicillin
Insect venom
Mechansim of
action
After degranulations,
histamine and other inflammatory
mediators are produced.
What's significant about them?
Histamine
Performed in granules
Prostaglandins and leukotrienes
Formed after activation
1ry mediator
Immediate reponse
within 30 mins
Mast cells control immediate response

2ry mediator
Longer response
Neutrophilis and esnophilis control late or chronic response

1ry Mediator
2ry Mediator
Treatment for type 1
Immunotherapy by desensitization
(Allergy shots)
Antihistamines as diphenhydramine (Bendaryl) - blocks histamine receptors
Epinephrine -prolongs or increases cAMP levels in mast cells which inhibits degranulation.
Non-steroidal anti-inflammatory drugs
There's a difference between a localized allergen reaction and a true
anapylactic shock !
Anaphylaxis
is a severe, life threatening
whole-body allergic reaction
to a chemical that has become an allergen. Anaphylaxis happens quickly after second exposure.
What causes
an
anaphylatic shock
?
Within minutes of exposure an to an allergen anaphylatic reaction occurs
Angioedema
Constriction of airways making it difficult to breath
Dilation of blood vessels causing a systemic drop in blood pressure
How to save a life?
Adrenaline auto-injectors (Epipens) are prescribed for those believed to be at risk
If all these things happen together and you don't respond
immediately
you might
DIE
!
How to test for Anaphylaxis?
Skin testing
Another example of type 2 hypersensitivity is Erythroblastosis fetalis
It's caused when an RH- mother carries an RH+ fetus, and effect of treatment with anti-Rh antibody, or Rhogam
What are the signs and symptoms of erythroblastosis fetalis ?

Type II hypersensitivity
(or cytotoxic hypersensitivity)
And ......

ACTION !
Setting: Hospital
What happened to the patient?
Well, this is called Serum sickness and it's an example of
Type III hypersensitivity
.
Signs and symptoms
of Serum sickness
Fever
Rash
Joint pain
Itching
Treatment
Corticosteroid creams or ointments
Antihistamines drugs
NSAIAs
After treatment, the symptoms usually go away within a few days.
We're not done yet
Last but not least ...
Type IV Hypersensitivity
(Delayed Cell-Mediated)
Referred to as delayed because it takes a few days to develop.
It involves Th1 cells attracting and activating macrophages




Mechanism of
action
Thank you


Hadir Yousry
Hind Khaled
Yara El Messiry
Yara Refaat
Yara Samy
Yara Tarek
Chemotherapy drugs (hapten)
Drug Induced Cyctotoxic reactions

Symptoms
Treatment
Idiopathic ThrombocytopeniaPurpura
7
It's not only antiserum which causes Serum sickness
Rituximab
Anti-thymocyte globulin
Serum sickness likes reactions

It has similar symptoms to serum sickness, but in which immune complexes are not found
Cefaclor
Amoxicillin
Cotrimoxazole
Ciprofloxacin
Famous drugs:

ROLE PLAY
Setting: Hospital
In severe cases
Statistics
There are 1 in 5 people who suffer from hypersensitivity in the US
Full transcript