Immunology 2 Flashcards
Describe the 4 types of hypersensitivity reactions
Type 1 – IgE mediated drug hypersensitivity
Type 2 – IgG mediated cytotoxicity
Type 3 – Immune complex deposition
Type 4 – T cell mediated
Describe the process Type 1 Hypersensitivity reaction
Needs prior exposure to antigen/drug
IgE antibodies formed after exposure to molecule
IgE becomes attached to mast cells/leucocytes, expressed as cell surface receptors
Re-exposure cause mast-cell degranulation and releases inflammatory tings like histamine, prostaglandins, leukotrienes, platelet activating factor
Describe some signs/symptoms of Anaphylaxis
Rapid onset
Breathing difficulty, wheeze, cough, SOB
Hypotension
Circulation problems - low BP, high HR
Rash/Hives (itchiness)
Swelling of lips, tongue, throat
Loss of consciousness
Cyanosis
How common is it to have a biphasic response with anaphylaxis?
1-20% of people have biphasic response
Describe the process of a Type 2 Hypersensitivity reaction
Antibody dependent
Drug/Metabolite combines w/ protein
Body treats it as foreign and forms antibodies (IgG, IgM)
Antibodies combine w/ antigens
Complement system activates, damages cells
Describe the process of a Type 3 Hypersensitivity reaction
Immune complex mediated
Antigen/antibody forms large complex and activates complement system
Small blood vessels damaged/blocked
Leucocytes attracted to site of reaction
They release inflammatory substances
Example of a Type 3 Hypersensitivity reaction
Glomerulonephritis
Vasculitis
Example of Type 1 H reaction
Anaphylaxis
Example of Type 2 H reaction
Haemolytic anaemia
MS
Pemphigus
KEY symptoms of Anaphylaxis?
ABC PROBLEMS
AIRWAY
BREATHING
CIRCULATION
Describe the process of Type 4 Hypersensitivity reaction
Lymphocyte mediated
Antigen specific receptors develop on T lymphocytes
Leads to local/tissue allergic reaction
Example of Type 4 H reaction
Contact dermatitis
Stevens Johnson syndrome
Treatment of Anaphylaxis
Basic life support (ABCDE!!)
Stop drug if infusion
IM ADRENALINE 500MG
(300mg in epipen)
High flow O2
IV fluids - to ↑ BP
If no response after 5 mins, do IM again
What blood test can you do to confirm anaphylaxis?
When would this test be done?
Mast cell tryptase
AFTER treatment, otherwise Px will die
Difference between Immune and Non-immune anaphylaxis
NON-immune is due to direct mast cell degranulatin
No prior exposure
but clinically identical
What does adrenaline do?
Vasoconstriction - ↑ Peripheral vascular resistance, ↑ BP, ↑ Coronary perfusion
VIA alpha-1
Stimulates Beta-1 positive ionotropic and chronotropic effects on heart
↓ Oedema and bronchodilates VIA beta-2
Releases further mediators from mast cells and basophils by ↑ Intracellular c-AMP
∴ ↓ Release of inflammatory mediators
RF for hypersensitivity reaction
F
EBV, HIV
Prev drug reactions
Uncontrolled asthma
Medication (w/ macro molecules)
Certain HLA groups
Acetylator status
What are the clinical criteria for an allergy to drug
No correlation with pharmacological properties of drug
No linear relation w/ dose (Even a tiny amount will cause anaphylaxis)
Has a primary exposure
Small number of patients
Happens on re-exposure
Give examples of polymorphonuclear leukocytes
Neutrophils
Eosinophils
Basophils
Give examples of mononuclear leukocytes
Monocytes
T-cells
B-cells
What is the key role of monocytes?
Plays important role in innate and adaptive immunity (phago and Ag presentation)
Removes foreign or dead bodies
What are the 2 main intracellular granules in neutrophils?
Primary - kills microbes by secreting toxic substances
&
Secondary
What are neutrophils involved in?
Play important role in innate immunity (phagocytosis)
Where do macrophages reside?
Reside in tissues
e.g. Kupffer cells in liver, microglia in brain
What is the approx lifespan of macrophages?
Months/years
Main role of macrophages?
Remove foreign bodies and self (dead/tumour cells)
Presents Ag to T-cells
Approx lifespan of eosinophils
8-12 days
What dye is used to stain eosinophil granules?
Acidic dyes (eosin)