CMB2004 Cell and Molecular Biology of the Immune System Flashcards
What is specific immunity mediated by?
B and T lymphocytes
What are BCR expressed by?
B lymphocytes
What are TCR expressed by?
T lymphocytes
Which are found only in the membrane form, BCR or TCR?
TCR
What do BCRs bind?
“Free” antigens
What do TCRs bind?
Peptide fragment (epitope) bound to MHC expressed by APC
Describe the structure of antibodies
-Paired Variable (V) regions form two identical antigen binding site
-Constant regions are responsible for antibody structure and interacting with other molecules (FcR) and cells of innate system.
What are antibodies responsible for?
-Agglutination (against pathogens)
-Activating complement
-Activating effector cells
What are the two types of Light chain in antibodies?
Lambda or Kappa
What are the 5 isotypes of antibodies?
IgM, IgD, IgA, IgG and IgE
How many domains are found in the Light chain of an antibody?
2
How many domains are found in the Heavy chain of an antibody?
4 or 5
What comprises each domain in an antibody?
~110 amino acids
-Two Beta sheets
-Linked by a disulphide bridge
-Domains are paired
Name some compounds found in the immunoglobulin superfamily
TCR, MHC class I and II, CD4, CD8
How many hyper variable regions are found in antibodies?
3 in Variable Heavy and Variable light domains
What do the hyper variable regions found in antibodies contribute to?
Complementary determining regions (CDR1-3)
What types of epitopes are there?
Continuous or conformational
Describe the structure of TCRs
-Heterodimer of ⍺ or β chain (sometimes γ or 𝛿)
-Each chain has a V and a C region
-Domains are Ig like
Which cell types are MHC Class I molecules expressed by?
Nearly all cell types in body
Which cell types are MHC Class II molecules expressed by?
Specialised group of immune cells
-ANTIGEN PRESENTING CELLS
Describe the structure of MHC Class I molecules
Heterodimer of ⍺ chain (consisting of ⍺1, ⍺2, and ⍺3) and β2-microglobulin
What are the three different MHC Class I molecules?
HLA-A, HLA-B and HLA-C
What are the different HLA molecules encoded by?
Separate ⍺ chain genes
What do the ⍺1 and ⍺2 domains of MHC class I fold to form?
β sheet structure known as peptide binding site