Original Immunology Flashcards
What is the acronym ACID with regard to types of hypersensitivity reactions?
A - anaphylactic, allergic, atopic
C - cell-mediated, cytotoxic
I - immune complexes
D - delayed
With regard to HLA, which are up-regulated and which are down-regulated in pregnancy?
Down-regulated = HLA-A and HLA-B
Up-regulated = HLA-E and HLA-G
How does the placenta inhibit complement protein?
DAF, MCP and CD59 expressed on the placenta inhibit complement proteins
With regard to T-helper (Th) cells, which increase and which decrease in pregnancy?
Th1 = decreased, rheumatoid improves in pregnancy, malaria/herpes worsen
Th2 = increased, therefore SLE exacerbated during pregnancy
Which Ig has a pentameter structure?
IgM
Which Ig’s have a monomer structure?
IgA, IgD, IgG, IgE
Which Ig has a dimer structure?
IgA - can have either a dimer or monomer structure
What are the 3 professional APC’s?
1) Dendritic cells
2) Macrophages
3) B-cells
Following potentially sensitising events, within what time frame should anti-D Ig be administered?
As soon as possible, always within 72 hours
When is anti-D Ig prophylaxis indicated at <12/40 gestation?
1) Ectopic pregnancy
2) Molar pregnancy
3) TOP
4) Uterine bleeding which is repeated and heavy or associated with abdominal pain
What are the potentially sensitising events beyond 12/40 gestation that require anti-D?
1) Amniocentesis / Chorionic Villus Sampling
2) APH / PV bleeding
3) Abdominal trauma
5) ECV
6) Ectopic
7) Evacuation of molar pregnancy
8) Delivery /Stillbirth/ Miscarriage/ TOP
9) In-utero interventions, e.g. surgery, lasers etc.
Which Ig crosses the placenta?
IgG
Which Ig is the first to be produced by the neonate?
IgM
Which Ig is passed through breast milk?
IgA
What are the common products of the the 3 complement pathways?
C3, cleaved to C3a and C3b
What is the role of C3b?
1) Opsonisation
2) Forms C5 convertase (with other proteins) which cleaves C5 to C5a and C5b
What does C5b do?
Recruits C6, C7, C8 and C9 to form MAC - membrane attack complex
What is an allograft?
An allograft is where tissue from a different individual of the same species is used - i.e. a foetus is a natural allograft
At what gestation does maternofetal IgG start?
Week 12
At what gestation does the fetus start producing IgM?
Weeks 10-11
What does Th1 produce?
TNF-alpha, IFN-y and IL-2 - therefore since Th1 is suppressed in pregnancy, these are all reduced during pregnancy
What does Th2 produce?
IL-4, IL-5, IL-9, IL-10 and IL-13 - since Th2 production increases during pregnancy, these also increase during pregnancy
What are some examples of attenuated vaccines?
1) MMR
2) Polio
3) BCG
What are some examples of inactivated vaccines?
1) Hep A
2) Pertussis
3) Influenza
What are some examples of toxoid vaccines?
1) Tetanus
2) Diptheria
What is an example of a subunit vaccine?
Hep B
What is the innate immune system?
The immediate and non-specific response to attack
What is the adaptive immune system?
The more complex and specific response to antigens and generates immunological memory
What are the cells of the innate immune system?
Macrophages, neutrophils, natural killer cells
What are the cells of the adaptive immune system?
T-helper cells, B cells
What is the role of IgE?
Activates mast cells
At what gestation should a pregnant woman receive her whooping cough vaccination?
27-36 weeks
What are some examples of type I hypersensitivity reactions?
Anaphylaxis, atopy, allergic asthma
What are type I hypersensitivity reactions caused by?
IgE mediated degranulation of mast cells, triggered by antigen binding. Effects in <30 mins
What are some examples of type II hypersensitivity reactions?
Transfusion reaction, rhesus incompatibility
What are type II hypersensitivity reactions caused by?
Cytotoxic. Antigens cause IgM and IgG formation which bind to surface of target cells and then destroy it by complement. Effects 5-12 hours
What are type III hypersensitivity reactions caused by?
Immune-complex mediated. Effects 3-8 hours
What are some examples of type IV hypersensitivity reactions?
Contact dermatitis
Tuberculin
Granulomatous
(Autoimmune) - T1DM, Coeliac