Immunology Flashcards
Important immunoglobs in neonates
- IgA is resistant to stomach acid and found in large amounts in breast milk.
- IgG is the only Ig that can cross the placenta so is key for passive neonatal immunity
- When the neonate starts synthesising its own Ig it is IgM that is produced first.
IgA
Key in neonatal immunity as secreted in breast milk and resistant to stomach acid breakdown
IgD
Role as antigen receptor on B-cells
IgE
Role in allergic response
Protection in parasitic and fungal infections
IgG
Most common antibody type in circulation (approx 75% circulating Ig)
Key to fetal immunity as crosses the placenta
Maternofetal IgG transfer starts around week 12.
IgM
Produced in early response to pathogens i.e. before IgG
First antibody type to be synthesized by neonates
Fetal productIon IgM starts around week 10 to 11.
Hypersensitivity type 1
IgE
Fast Response < 1 hour after exposure
Antigens bind to IgE causing release of bioactive molecules
Anaphylaxis
Allergic asthma
Atopy
Some allergies eg latex
Hypersensitivity type 2
IgM,IgG,Complement
Ig binds to host cell antigen perceived as foreign
Activates release of cytotoxic mediators e.g. MAC
Autoimmune haemolytic anaemias
ITP
Goodpasture’s syndrome
Hypersensitivity type 3
IgG
IgG binds to antigens forming an immune complex
The immune complex often deposits in vessel walls triggering inflammatory mediators
SLE
Rheumatoid Arthritis
Hypersensitivity type 4
T-Cells
Delayed Hypersensitivity
T-cells sensitised by antigen presented by APCs
Memory T-cells activated after re-exposure
T-cels active macrophages
Contact Dermatitis
Graft Rejection
Multiple Sclerosis
Type 1 Diabetes
type IV reaction basis for Mantoux test
Hypersensitivity reaction type 5
IgM,IgG,Complement
Instead of antigen binding antibody binds cell surface ligands preventing cell signalling
Myasthenia Gravis
Graves Disease
What immune cells increase and decrease in pregnancy
Helper T lymphocytes can be Th1 and Th2.
Th1 is suppressed in pregnancy.
Th1 produces cytokines TNF-alpha, IFN-y and IL-2
»>TNF-alpha, IFN-y and IL-2 had damaging effects in some cases resulting in fetal death
Th2 increases
Th2 produce cytokines IL-4, IL-5, IL-9, IL-10 and IL-13
»» IL-3 and IL-10 enhanced fetal survival and promote
Immune Tolerance in Pregnancy
- MHC (HLA complex)
In very basic terms during pregnancy at the trophoblast:
HLA-A and HLA-B are downregulated
HLA-E and HLA-G are upregulated - Complement Protein Inhibition
DAF, MCP and CD59 are proteins expressed by the placenta that inhibit complement proteins. Complement is an important part of the immune system in graft rejections.
3.T-cells/T-helper cells
Changes to both the cell populations occur during pregnancy. Increased T regulatory cell (TREG cell) populations occur in pregnancy. These cells can both up and down regulate various immune responses.
Th2 levels increase during pregnancy
Th1 levels decrease during pregnancy
- Phosphocholination
The addition of the phosphocholine molecule to glycoproteins inhibits T and B lymphocyte responses. It is a mechanism used by some parasites - PDL1
Cell signalling molecule that down regulates T-cell response - Progesterone
Thought to play a role in immune suppression by stimulating lymphocytes to produce a blocking factor that mediates cytokine production.
Other mechanisms
Placental exosomes, retroviral envelope proteins and CRH may all play a role in maternal immune tolerance but this level of detail is unlikely to be required by the MRCOG
When and who is routine antenatal prophylaxis with anti-D Ig (RAADP) offered to?
All RhD negative pregnant women who have not been previously sensitised
Single dose regimen at around 28 weeks, or two-dose regimen given at 28 and 34 weeks
indications to give anti d Ig prophylaxis in <12 weeks gestation
ectopic pregnancy
molar pregnancy,
termination of pregnancy
uterine bleeding where there is repeated, heavy bleeding or associated with abdominal pain.
The minimum dose should be 250 IU.
Live vaccines
Vaccines not usually advised in pregnancy (live vaccines)
MMR
BCG (TB)
Varicella
Polio (oral)
Rotavirus
Yellow fever
Typhoid (oral)
Cholera (oral)
Inactivated Vaccines
Influenza
Hepatitis A
Pertussis
Toxoid Vaccines
Diptheria
Tetanus
Polysaccharide vaccines
HIB
Meningococcal A&C
Pneumococcal
Typhoid
Subunit/Genetically modified
Hepatitis B
Vaccines reccomended in pregnancy
flu
whooping cough
Dysplasia - 4 microscopic characteristics:
Anisocytosis (unequal cell size)
Poikilocytosis (abnormal cell shape)
Hyperchromatism (pigmentation)
Mitotic figures (increased cells currently dividing)
