Adaptive immune system Flashcards
What are the differences between innate and adaptive immune system?
- Adaptive can identify exactly which microbe is present by using antibodies rather than using the mannise receptor on the phagocyte
- they have different receptors but limited to toll like n-formyl methionyl receptor and mannose in innate and in adaptive can recognise antigens specfically
- innate receptors are nonclonial but with adaptive they can make billions of receptors
What is the T-cell receptor composed of?
Alpha and beta chains, some are conserved and some are variable
What occurs at the variable region of the t-cell recptor?
The antigen binding
When will the TCR recognise the antigen?
When it is present by an MHC
What is a MHC complex?
They are peptide-binding cell surface proteins they starbd for major histocompatibility complex
What is a HLC-complex? How many are there ?
The same as a MHC in humans theres 2 types class one and class two
Which cells express MHC-class-I?
- on all cells with nucleus
- high expression on lymphocytes
- low expression on non lymphoid cells
Which cells express MHC-class-II?
- not on all cells
- high expression on antigen presenting cells (dentritic cells, macrophage, B cells, activated T-cells
What is the peptide-binding cleft?
It is where the peptide can bind to the MHC molecule
What is CD8?
It is a protein found on cytotoxic T-cells
What needs to occur for the antigen to bind to a T-cell?
-MHC class I needs to have CD8 bound
What activates cytotoxic T-cells?
MHC class I
What is CD4?
Protein found on helper T-cells
What are some features of MHC molecule?
- bind 1 peptide at a time
- bind only peptide
- low affinity
- broad specificity
- only stable on Cell surface membrane if bound to peptide(antigen)
What do lymph nodes have ?
Lots of B cells and Tcells
What cell gets an antigen to the lymph nodes?
Dendritic cells
What do dendritic cells do?
- Sit in our tissue They eat up microbes they come across and take them to the lymph node and show the cell to lots of T-cells
- antigens in our blood strem are captured by antigen presenting cells in the spleen
What happens when a cell is infected by an intracellular microbe?
- they are capturered by an antigen presenting cell
- antiges are then broken down and presented in association with the MHC molecule of the APC.
What is pathway for an antigen in the body? CD4
- endocytosis of the microbe occurs
- the microbe is now in a vesicle in the cell
- fusing with a lysosome forms a phagolysosome where the microbe is broken down into different peptides
- these broken down peptides will bind to a MHC class II molecule
- the complex is then transported to the cell SM where it can now activate CD4+ Tcell
What is the pathway for an antigen in the body? CD8?
- occurs when microbe is infecting the cell and makes its way into the cell on its own (not via phagocytosis)
- microbial proteins are made and some of the peptides will bind to MHC class I molecule
- they go to the ER to golgi and transported on the cell surface membrane to be recognised by CD8+ CTL
How are antibody diversity reached?
- combination of genes
- combination of heavy and light chains
- somatic hypermutation
What increases the most when presence of antigen occurs on graph?
IgG
What is IgG?
Type of antibody found in the blood and other body fluid and protects use from bacterial and viral infections. It takes time to form after an infection or immunisation.
What is IgM?
Type of antibody mainly found in the blood and lymph fluid. Its the first antibody made to fight an infection
Why do we want B- cells that produce high affinity antibodies?
-as they can bind to the dendritic cells and recieve the anti-apoptosis signal and stay on as plasma cells and memory cells using
