Immunology Flashcards
What type of vaccine is HPV vaccine?
Recombinant (uses virus-like particles)
Protects against 9 types of HPV: 6, 11, 16, 18, 31, 33, 45, 52 and 58.
MMR vaccine type
Live attenuated
Which complement is common to all pathways?
C3
Growth factor in granular tissue in a wound
VEGF
Which Immunoglobulin is a pentamer?
IgM (Ig with highest molecular weight)
IgG: % of total Ig pool? Structure? Subtypes?
75% total Ig pool
Monomer
4 subtypes: IgG1, IgG2, IgG3, IgG4
IgA: % of total Ig pool? Structure? Isoforms? Where is it found?
20% total Ig pool
Dimer
2 isoforms
Found in mucosal epithelium (GIT, respiratory tract, urogenital tract)
IgM: % of total Ig pool? Structure? Where is it found?
5% of total Ig pool
1st Immunoglobulin produced during infection, pentamer, confined to intravascular pool
IgE: Structure? Function?
Monomer
Binds to basophils and mast cells
Involved in allergy and parasitic infections
IgD: % of total Ig pool? Structure?
<1% total Ig pool
Monomer
Hepadnavirus containing DNA, can be transmitted via needle sharing and blood transfusion
Hep B
Interpretation of Hep B serology
HBsAg (surface Ag)= current infection (acute/ chronic = >6 months)
HBeAg= acute (early) infection
anti HBe Ab = indicates acquired natural immunity (from previous infection only)
anti HBs Ab = immunity (either previous infection or vaccination)
Anti HBc Ab (IgM)= acute infection, early or resolving
Anti HBc Ab (IgG)= acute/ chronic/ immune (immune secondary to infection, not vaccination)
Main cell types in the adaptive vs innate immune system
Adaptive (acquired): B and T cells that have immune memory
Innate: NK cells and some types of T cells (gamma and delta)
Rhesus D immunoglobulin treatment utilises what class of antibody?
IgG
What type of vaccination is the varicella vaccine?
Live attenuated
Examples of live/ inactivated/ toxoid/ polysaccharide and subunit/ GM vaccines?
Live: MMR, varicella, BCG, polio, rotavirus, BCG, typhoid, cholera
Inactivated: influenza, Hep A, pertussis
Toxoid: diphtheria, tetanus
Polysaccharide: HIB, meningococcal A&C, pneumococcal, typhoid
Subunit/ GM: hep B
Why does RA improve in pregnancy and SLE worsen?
Progesterone suppresses Th-1 cells and RA is Th-1 dependent
Humoral immunity tends to dominate (Th-2 cell mediated) and SLE is Th-2 dependent.
How does the placenta help to prevent immune rejection of the foetus?
The foetus is a semi-allograft
The placenta acts as an immunological barrier between the mother and the foetus. It is able to tolerate foreign antigens without provocation of immune response. A number of mechanisms help with this:
- MHC (HLA complex) antigen expression:
- In trophoblast cells MHC class II antigens are not presented
- MHC class I HLA genes can be classed as 1a (HLA-A, -B and -C) or 1b (HLA- E, -F, and -G)
- In extravillous trophoblast cells only HLA-C is expressed from 1a group along with all three types of 1b genes (-E, -F and -G)
- HLA-G in particular has several roles in immune suppression such as reduction of NK cell killing activity, reduction of IFN-y production, regulation of cytokine production and suppression of cytotoxic T lymphocyte killing activity and T-helper activity - Complement Protein Inhibition
- DAF, MCP and CG59 are proteins expressed by the placenta that inhibit complement proteins. Complement is an important part of the immune system in graft rejections. - T-cells/ T-helper cells:
- changes to both the cell populations occur during pregnancy. Increased T regulatory cell (TREG cell) populations occur. These cells both up and down regulate various immune responses.
- Th2 levels increase during pregnancy
- Th1 levels decrease during pregnancy - Phosphocholination:
The addition of phoshocholine molecule to glycoproteins inhibits T and B lymphocyte responses. - 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
At what gestation foes maternal IgG transfer to foetus start?
12 weeks
At what gestation does fetal production of IgM start?
Week 10-11
Which is the first antibody type to be synthesised by neonates?
IgM
Which Ig is secreted in breast milk and resistant to stomach acid breakdown?
IgA
Which Ig crosses the placenta?
IgG
What are APCs? What are the three types?
Cells that have MHC class 2 molecules in addition to type 1 and are able to stimulate CD4+ (T helper cells) and CD8+ (Cytotoxic T cells)
3 types:
- Dendritic cells
- Macrophages (derived from monocytes)
- B cells