10.4 The Adaptive Immune System: Humoral & Cell-Mediated Immunity Flashcards
Can CD4 and CD8 T cells recognise antigens if these antigens are in their natural form?
“Nuh Uh”
They can only recognise antigens that are processed and presented to them through their T-Cell receptor
What is the role of Major Histocompatibility complex?
- Binds to processed antigens
- Enables T cells to recognise antigens at their TCRs
Draw a diagram of antigen processing and presentation of a peptide
10.4.docx
Which MHC class presents to which type of T cell?
Class 1: CD8
Class 2: CD4
Which MHC class corresponds to endogenous and exogenous peptides?
Class 1: Endogenous
Class 2: Exogenous
Describe an MHC class 1 molecule. What type of cell is it presented on?
- Yellow Alpha Protein (1,2 and 3)
- Blue Beta 2 microglobulin (not covalently associated)
- Expressed on nucleated cells
Describe an MHC class 2 molecule. What type of cell is it presented on?
- Dark Alpha Protein (1 and 2)
- Light Beta protein (1 and 2)
- Expressed on antigen presenting cells
Draw a diagram of antigen processing with MHC class 1
10.4.docx
Where does the CD8 domain bind to MHC class 1?
Alpha 3 (bottom left yellow)
Where does CD4 bind to on MHC class 2?
Beta 2 (bottom right light)
WHat are the two receptor components that bind to MHC on both CD8 and CD4 T cells?
Alpha TCR and Beta TCR
In what situations is MHC class 1 useful? What happens when the antigen is presented?
Useful for intracellular pathogens/tumour. Leads to production of cytotoxic T cell
In what situations is MHC class 2 useful? What happens when the antigen is presented?
Useful for extracellular pathogens. Leads to production of helper T cells.
Draw an immunoglobulin, label the chains, disulphide bonds, and antigen binding sites
10.4.docx
What are the five types of immunoglobulin
GAMED
Which is the first Ig to be secreted? Where can it bind to antigens?
- IgM
- Binds to antigens in blood and tissue
Draw the structure of IgM. Describe it’s structure
Check diagram (+ “pentameric; 10 antigen binding sites”)
On what encounter with an antigen is IgG secreted more?
Second encounter (B cell changes from IgM to IgG, refining itself in the process)`
Draw an IgG molecule and list off as many facts about is as you can
10.4.docx
Which receptors do IgG antibodies bind to?
Fc receptor on amcrophages and neutrophils
Why is sIgA called sIgA?
SECRETORY:
In mucosal secretions. Binds to antigens. Secretory component prevents it from breakdown by enzymes, giving it time to bind
Is IgA monomeric or dimeric? Therefore, how many binding sites does it have?
Dimeric, four binding sites
Draw sIgA
10.4.docx
Draw a flow chart of B cell maturation
10.4.docx
What sites do antibodies bind to on antigens?
Epitopes
raw the eq rxn for agab complex formation
Ab + Ag <> AbAg complex
What are the four functions of antibodies
- Neutralisation
- Agglutination
- Opsonisation (FcR -> enhances activation)
- Classical Complement Activation (punching hole)
What is “specificity” of B cells?
when one b cell will specifically bind to one antigen
What happens after a B cell is activated? What is this called?
It proliferates itself in multiple rounds (this is known as clonal proliferation)
What do B cells differentiate into following clonal proliferation?
- Memory B cells expressing IgG
- Plasma cell (secretes IgM antibodies)
What Ig isotype is on undifferentiated b cells?
IgM
What Ig isotype do plasma cells from differentiated memory cells produce?
IgG
Draw a Primary antibody graph including IgM and IgG
10.4.docx
List the four steps in the initial humoral response
- Recognition
- Activation
- Clonal proliferation
- Differentiation
Draw a secondary antibody graph including IgM and IgG
10.4.docx
Draw a flow chart of T cell development, including where each step occurs
- Haemoatopoietic Stem Cell differentiates into common lymphoid progenitor in bone marrow
- CLP enters travels through circulation to thymus
- Here is becomes a lymphoid progenitor cell
- Pre T Cells
- Mature Naive CD4 and CD8 T cells
- Circulation again
What is clonal selection?
The process by which one T cell is activated upon recognition of a complementary antigen
Draw a flowchart of T cell activation into effector cells
10.4.docx
Describe the role of helper T cells in activating B cells
- B cells present antigen to Th via MHC 2
- Th release cytokines to activate B cell
Describe the role of helper T cells in activating macrophages
Releases cytokines to:
- Increase phagocytotic activity
- Increase experssion of MHC II (extracellular)
After they leave the secondary lymphoid tissues, what local vascular changes permit Tc, Th and Ig from leaving the bloodstream? Can they leave otherwise?
- Vasodilation
- Increased vascular permeability
- No, they cannot leave otherwise
Describe the mechanism by which Tc kill inflected cells via apoptosis
- Recognises unusual cell and forms an enclosed seal (with a gap)
- Perforins and granzymes released from granules
- Perforins perforate, creating channels through which granzymes travel
- Granzymes initiate apoptosis
Which types of cells are involved in antibody-dependent cell cytotoxicity?
- Neutrophils
- Macrophaghes
- NK cells
- Eosinophils
