Humoral (II) Flashcards
Explain how antibodies are produced from the lymph nodes
Antigen comes into contact w BCR and activates B cells (complementary via clonal selection)
B cell differentiates and proliferates into memory B cells complementary/clones and also plasma cells which then secrete Bcr forming antibodies
What are the disulfide bonds between
H-H and H-L chains
How many variable VH and VL are there (antigen binding site)
2 of each (VL VH. VH VL)
Which chains can be glycosylated
Heavy chains
How many Constant light CL domains are there always
1
Do domain number of CH differ between antigens
Yes, can be 3 or 4 CH domains
What are domains
Folded globular units of proteins which can have functional units eg binding sites VL and VC
How many amino acids make up globular unit domains on ig
110
Which bond is present in domains
Disulfide bonds
What makes up the VL and CL (Vl 1 Cl 1)
2 beta sheets (globular domains) joined together and intrachain joined via disulfide bonds
Why are VL and VH antigen bs called HYPERVARIABLE sites
They have variable (HV) regions
How many hyper variable regions are there at VH and VL which determine specificity for antigen
3 for VH and 3 for VL = 6 in antibodies all together
Where are ig domains also found (not just in antibodies)
T cell receptors ( alpha and beta domains)
Mhc molecules
Cell adhesion molecules
What are the 5 antibody isotypes
M A D G E
Mu, alpha , delta , gamma, epsilon
What is an antibody isotype differentiation
The CH region only. The rest is same
What are the 2 types of light chain called
Kappa and lamda
What is antibody valency
Number of antibody valency / binding sites eg igm has 10 (it has 5 ig) most have 2
What holds 5 ig together to form Igm
J chain
Why isn’t Igm a problem for donation of blood
Can’t cross placenta
Which ig is produced FIRST IN PRIMARY RESPONSE ALWAYS
Igm ( then branches off to others)
How many domains does the mu / heavy chain on Igm have
5- 1 x VH
4 x CH
Which antibody has high avidity
Igm
How is Igm low affinity improved
Pre affinity maturation
What is missing on an Igm
Hinge region between fab and fc
What is Igm main function
C1q activation and opsonisation
How many domains does igG have on its gamma Heavy chain
4- 1 x VH 3 x CH
Which antibody is most prevalent in serum
IgG
Which antibody is most likely in the secondary response (first is Igm)
IgG
How many subtypes of IgG is there and why
4
They are produced at diff times, structure different and hinge is different
How many IgG are needed for c1q activation
2
How does IgG allow passive immunity
Can cross the placenta from mother
How does iga travel different in serum than mucosa
Monomer in serum
Joined by J chain to form a dimer in mucosal surfaces
Which cells give iga a secretory component to get to mucosal sites
Epithelial cells
How many domains does a chain have on iga
4
1 VH 3 CH
Which subtype of iga is in serum and which in mucosa as a dimer
Iga 1 is serum
Iga 2 dimer in mucosa
How does iga dimer form protection on mucosal surfaces
Stops pathogen adhesion
Neutralises toxins By binding and macrophages
Stops commensals entering blood
Where is iga predominant
In secretions such as milk
Which 2 antibodies are lowest in serum
D and E (e lowest)
Which 2 ig can be co expressed on Bcells as bcr together
Igm and igd
What do igd stimulate basophils and mast cells to release
AMPs eg defensins
How many domains does delta have
4
1 VH
3 CH
How many domains does Ige have
5
4 CH like Igm does
What is the most important job of ige
Bind to fc receptors on basophils and mast cells and cause histamine degranulation
Why do antibodies ige cause anaphylaxis
Release of histamine causes circulatory shock
Which area is there no Ig
Brain
Which 2 are present in serum most (ecf)
IgG and igA monomer
How can antibody switching occur from Igm to others
Dna cleavage of the constant heavy chain
Are the different isotypes for constant heavy on different genes
Yes but same chromosome
