Lecture 1 Flashcards
What is specific/adaptive immunity induced by?
Exposure to a particular infection
What are some features of specific immunity?
Mediated by lymphocytes (B/Tcells)
How can self reactive lymphocytes be removed?
By clonal deletion
What forms a clone of effector cells?
Proliferation and differentiation of activated specific lymphocytes
Why are BCR expressed by?
B cells
What does the membrane bound form of Ig binds?
Free antigen
When is the antigen secreted?
When the B cell is activated
What allows for the activation of complement?
Opsonisation and classical pathway activation and MAC
What are antibodies formed by?
4 polypeptides
What is the structure for antibodies?
Variables V regions (heavy and light) and constant C regions
What do the two V regions form?
Antigen binding site
What do the C regions do?
Antibody effector function - FC region
What type of structure are antibodies?
Bivalent structure
What are the 2 identical heavy and light chains held together by?
Covalent and non covalent bonds
What does the FC region bind on the constant region?
Macrophages, NK cells and neutrophils
What are the 5 different classes of antibodies?
IgA, M, D, G, E
What is another word for antibody?
Isotype
What are antibodies determined by?
The heavy chain in the C region
What termini’s do C domains occupy?
Carboxyl
What C termini’s do V domains occupy?
Amino
What domains are part of the immunoglobulin superfamily?
TCR, MHC class I and II
How many hypervariable regions are there?
2 in the V heavy and V light
How many HV loops?
6
How many complementary-determining regions are there (CDR)?
CDR1-3
What affects antibody binding?
Size and shape
What does a linear epitope mean ?
It s continuous
Non-linear?
Discontinuous
How are epitopes recognised?
By antibodies
What do antibodies and antigens form?
Non-covalent interactions
When might an antigen sequence be manipulated?
In a vaccine design
What do CDRs determine?
The specificity and affinity of an antibody for an antigen
What do TCR bind instead of antigens?
Peptides
What do TCR recognise?
Short peptide fragments bound to MHC molecules on other cells
What is the structure of TCRs?
They are made up of alpha and beta chains which form a heterodimer
What do the V domains of TCR interact with?
Peptide bound to MHC molecules
When were MHC molecules first identified?
In transplant rejection
Where are MHC I molecules expressed?
In nearly all cell types in the body
Where are MHC class II molecules expressed?
Restricted to specialised groups
Where are MHC class I molecules expressed?
On all nucleated cells
What are the 3 different MHC class I molecules?
HLA-A, HLA-B, HLA-C
What is the MW of the alpha chain in an MHC class I molecule ?
43kD
What is the MW of the beta-1 microglobulin chain on the MHC CLASS I molecule?
12kD
What do the alpha and beta domains fold to make on an MHC class I molecule?
Beta sheet - peptide binding site (groove, cleft)
What is the DNA encoding alpha 1 and 2 on MHC class I moelcules like?
Polymorphic
What is the alpha 2 chain and Beta2 domain like on MHC I MOLECULES?
Fold into Ig-like domains
What are the three types of MHC class II molecules?
HLA-DQ, HLA-DP, HLA-DR
What are the alphabeta chain domains expressed on in MHC CLASS II?
APC
