10. Immunology Revision Lecture - Ian Todd Flashcards
1
Q
- Explain the main things involved in innate immunity
- Explain the main things involved in adaptive immunity
- What kind of cell is usually an APC?
A
- PAMPs / PRRs
- Tc / Bc / antigen / APC / Ig
- Dendritic cell
2
Q
What is complement and what does it do?
A
Complements are proteins and they complement the effect of antibodies
3
Q
Describe how to get to C3 convertase via the 3 complement pathways
A
MBL pathway
MBL (mannon binding lectin) + microbial mannose
Activates serine proteases MASP-1 and MASP-2
Breaks down C4 and C2
C4b2a = C3 convertase
Classical pathway Antigen bound to antibody (IgG or IgM) bound to C1q Activates C1r and C1s Breaks down C4 and C2 C4b2a = C3 convertase
Alternative pathway
C3b + covalently bound to microbial surface + Factor B fragment b + properdin
C3bBbP = C3 convertase
4
Q
- C3b is constantly being made in the body but is rapidly degraded. What is this called?
- What can be done to stop the degradation?
A
- Tick over pathway
2. Stabilise by binding
5
Q
- Role of C3a?
2. Main role of C3b?
A
- Mast cell activation and neutrophil recruitment
2. Opsonisation
6
Q
- What 2 things split up C5?
- What is the role of C5a?
- What is the role of C5b?
A
- Mast cell activation and neutrophil recruitment
- Membrane attack pathway leading to membrane lysis
Membrane attack complex makes a hole in microbial membrane
Poly form of C9 + C6 / C7 / C8
7
Q
- What do T cells originate from?
- Th cells: express? Peptide on APC? Type of protein?
- Tc cells: express? Peptide on APC? Type of protein?
- How do you activate a T cell?
- What is the main APC for naive T cells?
A
- Lymphoid stem cells
- CD4+ / HLA class 2 / exogenous proteins
- CD8+ / HLA class 1 / endogenous proteins
- Activate signalling pathways in the T cell
- Myeloid dendritic cell
8
Q
- Activated Th1 cell: identify microbial peptide on what? Secrete what? Give an example.
- Activated Th1 and Th2 cells: drive which 2 things? What does it do to B cell + Ag + Ig?
- What is the majority of the cytokines that Th1 releases? What does it encourage the class switching to?
- What are the majority of cytokines that Th2 releases? What does it encourage the antibody production of?
A
- APC / cytokines / IFN gamma
- B cell activation and Ab production / internalises the complex into the cytoplasm
- IFNgamma
IgG (1-3) - IL4 / IL5 / TGFbeta
IgG(1-4) / IgE / IgA
9
Q
What are the two ways that a Tc cell can trigger cell death? What is the final outcome of these 2 methods?
A
Secreting perforins and granzymes
Expressing the Fas ligand
Apoptosis
10
Q
- T cell antigen receptor: polypeptide chains? Domains? Combining site? Function?
- What do Th cells do? What does this result in?
- What do Tc cells do?
- T cell recognition: what must the antigen be? Binding?
- How do Th0 cells polarise into Th1 and Th2 cells?
A
- 2 = Alpha and beta
Variable and constant
V-alpha and v-beta = antigen specificity - Help activate other cells of the immune system mainly B cells and macrophages leading to antibodies and phagocytosis
- Kill infected cells
- Protein
T cell can’t bind directly so the antigen has to go inside an APC, undergo antigen processing, and then be presented as a peptide on the surface of a cell - Th0 cells exposed to IL-12 polarise into Th1
Th0 cells exposed to IL-4 polarise into Th2
11
Q
What activates the APC?
What kills the APC?
A
Th cell + antigen activates APC
Tc cell + antigen kills APC
12
Q
HLA class 1
- Binds to which T cell?
- How many polypeptide chains and what are the called?
- Which chain is in the membrane of the APC?
- Which domains make up the peptide binding cleft?
A
- Tc cell
- 2 chains = alpha and beta
- Alpha chain
- alpha 1 and alpha 2 = peptide binding cleft
13
Q
HLA class 2
- Binds to which T cell?
- How many polypeptide chains and what are the called?
- Which chain is in the membrane of the APC?
- Which domains make up the peptide binding cleft?
A
- Th cell
- 2 = alpha and beta
- Both chains in membrane of APC
- Alpha 1 and beta 1 = peptide binding cleft
14
Q
Explain antigen processing with HLA class 2 and Th cells
A
Exogenous antigen Endocytosis (in a vesicle = endosome) Proteolytic enzymes pumped in Antigen broken into peptides ER is making HLA class 2 HLA class 2 has an invariant chain blocking the peptide binding cleft HLA 2 goes into endosome Proteolytic enzymes degrade invariant chain so peptide binding cleft open Antigen peptide binds to HLA class 2 Goes to cell surface
15
Q
Express antigen processing with HLA class 1 and Tc cells
A
Endogenous antigen Proteosome takes antigen into cytosol Broken into peptides ER is making HLA class 1 Antigen peptides are taken to HLA class 1 They bind and go to the cell surface
