Immunology Flashcards
Hypersensitivity reaction type I - Mechanism
Anaphylactic
antigen reacts with IgE ound to mast cells
Hypersensitivity reaction type II - Mechanism
Cell bound
IgG or IgM binds tp antigen on cell surface
Immune complex
Hypersensitivity reaction type III - Mechanism
Free antigen adn antibody (IgG, IgA) combine
Hypersensitivity reaction type IV - Mechanism
Delayed hypersensitivity
T-cell mediated
Hypersensitivity reaction type I - Examples
- anaphylaxis
- atopy (asthma, exzema, heyfever)
Hypersensitivity reaction type II - Examples
- Autoimmune haemolytic anaemia
- ITP
- Goodpasture’s syndrome
- Pernicious anaemia
- Acute haemolytic transfusion reactions
- Rheumatic fever
- Pemphigus vulgaris / bullous pemphigoid
Hypersensitivity reaction type III - Examples
- Serum sickness
- Systemic lupus erythematosus
- Post-streptococcal glomerulonephritis
- Extrinsic allergic alveolitis (especially acute phase)
Hypersensitivity reaction type IV - Examples
- Tuberculosis / tuberculin skin reaction
- Graft versus host disease
- Allergic contact dermatitis
- Scabies
- Extrinsic allergic alveolitis (especially chronic phase)
- Multiple sclerosis
- Guillain-Barre syndrome
Hypersensitivity reaction type V - Examples
Grave’s disease
Myasthenia gravis
Hypersensitivity reaction type V - mechanism
antibodies recognise and bind to the cell surface receptors (stimuating/blocking ligand binding)
classic presentation of infectious mononucleosis
sore throat
pyrexia
lymphadenopathy (ant and post triangles)
Maculopapular, pruritic rash after amoxicillin use
Other: hepatitis, transient rise in aLT; splenomegally; palatal petechia
diagnosis of infectious mononucleosis
heterophil antibody test (monospot test) in second week of illness
Exampels of live attenuated vaccines
measles, mumps, rubella (MMR)
BCG
influenza (intranasal)
oral rotavirus
oral polio
yellow fever
oral typhoid
How does a skin prick test for allergy work
- cheap and easy = most common
- many allergies - incl food and pollen
- incl histamine (positive) and sterile water (negative) control
- wheel develops if allergy present
- interpreted in 15mins
Radioallergosorbenst test (RAST) uses
- determines amount of IgE reacting with suspected/known allergens
- results in grade 0 (negative) - 6 (strongly positive)
- food, inahled (pollen) and wasp/bee venom
- blood test done when skin prick not suitable (extensive eczema/takign antihistamines OR hx of anaphylaxis)
skin patch testing for allergy uses
for contact dermatitis
patches with 30-40 allergens is applied for 48hrs - resutls read by dermatologists after another 48hrs
examples of inactivated preparations for vaccines
- rabies
- hepatitis A
- influenza (IM)
define live attenuated vaccines
weakened form of pathogen
CI: individuals with compromised immune systems
Define inactivated preparations of vaccines
pathogens have been killed
may require boosters to maintain immunity (weaker induced immune response compared with live attenuated)
Define toxoid vaccines
toxins made by bacteria are rendered harmless (detoxified) and used as antigens
require boosters
examples of toxoid vaccines
- tetanus
- diphtheria
- pertussis
Definte subunit or conjugate vaccines
subunit = part of pathogen used
conjugated = links the poorly immunogentic bacterial polysaccharide outer coats to proteins to make them more ommunogenic
Define messenger RNA (mRNA) vaccines
- piece of mRNA into cells to produce a protein to trigger an immune response
example of mRNA vaccine
- some COVID-19 vaccines
define viral vector vaccines
use harmless virus (different from target pathogen) to deliver cirtical parts of target pathogens
can be produced more rapidly in response to emerging threats
Viral vector vaccine examples
- some Ebola vaccines
- some COVID-19 vaccines
Common autosomal dominant bleeding disorder
Von Willibrand’s disease
Coag tests findings in Von Willebrand’s disease
- prolonged PT
- prolonged APTT - acts as a carrier molecule for favtor VII
- platelets normal - vWF required to promote platelet adhesion but platelets themselves not affected
+/- mild reduction in factor VII