Immunology 3 ( T Cell Mediated Immunity) Flashcards
Do T cells produce antibodies?
No
Do T cells produce secreted TCRs
No
What family are TCRs and Immunoglobulins members of?
The immunoglobulin superfamily
True are false: the variable domain on each t-cell differs?
True
Describe the make up of a T cell receptor.
Alpha chain and beta chain. Constant alpha and variable alpha and constant beta and variable beta
How do helper T cells help B cells?
Help them differentiate into Ig secreting plasma cells
How do helper T cells help macrophages?
Activates them so they can carry out phagocytosis and killing
What at T cells relationship with APCs?
T cells can not interact directly with antigens can only interact with antigens presented on cells (APC)
What is the only type of antigen T cells will recognise?
Proteins
What allows the antigen peptide to be presented on APCs?
A surface membrane protein called HLA in humans MHC in mammals
What is the mhc1 receptor made of?
Alpha 1,2,3 and a beta micro globulin
What type of T cells bind to HLA class 1 cells?
Cd8 cytotoxic T cells
What is the HLA class ii receptors made of?
Beta 1,2 and alpha 1,2. ( the 1’s are closest to the antigen)
What T cells bind to HLA class 2?
Helper T cells
What are the helper proteins for HLA-t cells interactions?
Cd4 (helper) and cd8 (cytotoxic)
What is cd8 made of?
Two polypeptide chains that bind to alpha 3 of the HLA class 1
What is cd4 made of?
It is a single polypeptide but with 4 immunoglobulin like domains ( part of superfamily) that bind to the side of the beta 2 domain of HLA 2
What are protein antigens in the cytoplasm degraded in?
A complex called a proteosome
How are peptides transferred the proteosome to the endoplasmic reticulum?
Via peptide transporter proteins.
What length are the processed peptides?
8 or 9 aa
Where do the processed peptides meet the newly synthesised HLA 1?
In smooth endoplasmic reticulum via peptide transporter gateways. Once complex they move to the surface
What happens after enocytosis of exogenous particles?
Internalised into a vacuole. Enzymes entering the vacuole degrade the antigen.newly synthesised HLA 2 is transported to vacuoles and complexed with antigen peptide aa
What processing do infected cells do?
HLA class 1 processing
What do B cells that have taken in bound antigen do?
HLA type ii processing- helper T cell comes and turns B cell into a plasma cell
Can most cells process HLA 1 and 2?
Most cells type 1
Mostly immune cells type 2
What types of cells express high levels of type HLA type 1 and 2?
Dendritic cells
What are cytokines?
Secreted proteins that regulate cellular activity
How do cytokines work?
By binding to cell surface receptors and triggering intercellular signalling pathways
State the 5 types of cytokines
1) interleukins
2) tumour necrosis factor (TNF)
3) interferons
4) colony stimulating factor
5) chemokines
What to TH1 cells do?
Drive cell mediated immunity through t-cells and macrophages
What IL does Th1 produce and what does it do?
IL-2 activates proliferation of T cells.
What interferon do th1 cells mostly produce and what does it do?
INF-gamma main function is to activate macrophages to activate and stimulate phagocytic digestive functions
What is the main objective of th2 cells?
Activation of B cells and production of antibodies (not to activate T cells and macrophages)
Do th1 and th2 work together?
No, they inhibit each others activity through their cytokines
What are th0 cells?
When Th cells leave the thymus they are not committed to being Th1 or Th2.
What determines if a th0 call become Th1 or Th2?
The cytokine signals it receives at time of activation with an antigen - polarisation!!!
What cytokine produces th1 and th2 cells?
IL-12 produces th1
il-4 produces th2
In lymph nodes where do T cells primarily locate?
The paracortex
Where do the B cells usually locate?
In the follicles
In the lymph nodes there do t-cells and dendritic cells usually interact?
Paracortex
Where do helper T cells and B cells interact?
At the edge of the follicles
In the paracortex what activates T and B cells??
Activation of antigen specific T cells by dendritic cells and activation of antigen specific B cells by T cells
How long does it take B cells to mature in the germinal centre?
3-5 days
What 4 steps are involved in maturation of a instead B cells?
1) division - increases with size of response
2) antigenic selection- increases affinity of response- bad B cells destroyed
3) class switching- increases effector functions
4) formation of plasma cells and memory cells
Do all plasma cells go back to site of infection?
No, some go to bone marrow and produce antibodies from there
