Flashcards in Pa20292 Deck (284)
Why are IgG antibodies so important?
Most abundant AB type in the circulation
For secondary immune responses
Microbes coated in IgG - opsonisation and complement activation
AB dependent cell mediated cytotoxicity
IgG provide Foetus with humoral immunity
What activates cytotoxic T cells ?
Antigen presenting cells of class I MHC
Usually present viral fragments
Can also be stimulated by T helper Th1 cells
What shapes do each of the different classes of antibodies have? Ie monomer, dimer....
Monomers= IgE IgG
Dimers = IgA
The lectin complement cascade pathway involves.....
Mannose receptor binding to lectin and cleaving C4
What receptors (ABs) do B cells express once matured but before class switching?
IgM and IgD receptors
Remember; class switching and somatic hypermutations improve antibody affinity and function
How are NKcs activated ?
IL-12 from macrophages
Activates NKCs, they secrete IFNy
IFNy Feeds back and activates macrophage
(positive feedback loop)
Some features of neutrophils?
Large multi lobed nucleus
Lot of organelles
Contain antmicrobial enzymes
Do therapeutic antibodies tend to be polyclonal or monoclonal?
Act against one particular epitope of an antigen
Activation of a single B cell= monoclonal response
Who were vaccinations discovered by and when?
By EDWARD JENNER
What cells is MHC protein present on?
Every cell apart from RBC's
What type of immunity do B cell produce?
Means antibody mediated immunity
Why do antibodies remain specific to a certain antigen for the rest of its life?
Because B cells undergo irreversible gene recombination to make it specific to a particular antigen, it can't change after this recombination as its irreversible.
What is inhibition of development of Th1 or Th2 cells by cytokine IL-4 and IL-12 known as?
When activated, B cells swell in size. We call them _____
Produces large numbers of antibodies
What do dendritic, macrophages and neutrophils have in common?
They are reactive oxygen and nitrogen species.
All engulf the antigen
Joining the constant region at the later mRNA stage in AB production, what does this allow?
Class switching at the later stages
The constant region of the heavy chain determines whether it's Ig A D M E or G
What do all 3 complement pathways result in the cleavage of?
C3--------> C3a + C3b
C3b leads to cleavage of C5--------> C5a + C5b
What classes can the 2 heavy chains of antibodies be?
Class A, D, E, G or M
What does high avidity of an AB mean?
They can bind a large number of AG's as they may be pentameric and have several binding sites, but usually bind with weak affinity.
Eg IgMs pentomer
What's HLA - B27 associated with?
Increased risk of ankylosing spondylitis
Majority of ppl with B-27 are healthy
What do lymphocytes have a large nucleus?
Involved with a lot of DNa transcription to make cytokines and antibodies
What are the only cells that can activate T helper cells?
Antigen presenting cells of class II MHC
igG antibodies are most abundant. Where Are these usually found?
In the circulation.
What cells do APCs present AG fragments to?
What are hypervariable regions also known as?
CDRs- complementary determining regions.
What are igA Antibodies for?
These target airborne antigens
Present at epithelial / mucosal surfaces (as this is where airborne antigens target)
Remember A for airborne
Generally found in lungs (we inhale airborne ABs)
Actions of T helper cells?
Activation of macrophages
Enhance recruitment of neutrophils
How do T cells decide whether to be cytotoxic T cells or T helper cells?
In the thymus T cells mature and encounter a range of self antigens
Once they engage with an MHC it helps to determine what they will become
Do IgG and IgE antibodies have low or high avidity?
They are monomers
Only have 2 antigen binding sites
But will have HIGH affinity