T-cells Flashcards
What is the most variable region on TCRs?
Where D and J segements join
Why is where D and J join the most diverse?
Due to junctional diversity - extra nucleotides added to the region
Whats an MHC?
Major histocompatibility complex
What are MHC molecules?
Molecules that bind to proteins from viruses and bacteria- then presents them to the T-cell ( called antigen presentation)
How many classes if MHC are there?
2
What are MHC class 1?
MHC molecules found on most nucleated cells- present antigens to cutotoxic T-cells
What are MHC class 2?
MHC molecules found on antigen presenting cells presents antigen to helper T-cells
What does it mean MHC genes being highly polymorphic mean?
High amoint of genetic diversity
What is an APC?
Antigen presenting cell
What are 3 types of APCs?
Dendritic cells
Activated macrophages
Activated B-cells
How are T-cells activated?
Dendritic cells take up pathogens and bring them to the lymphnode they interact wirh niave T-cell activating them into helper and cytotoxic T-cells
What are CD4 T-cells for?
They release cytokines that stimulate macrophages and CD8 T-cells
What are the two signals used in two signal model?
1)MHCs and TCRs
2)B7.1/7.2 and CD28
Without out these cells cant be killed
What is colonal expansion?
Production of many T-cells with T-cell receptors the MHC peptide complex. Production of a daughter cell from only one cell.
What does IL-2 cause?
Produced by T-helper cells cause proliferation into multiple more T-cells
What T-cell is cytotoxic?
CD8 T-cell
How does a T-cell become CD8 T-cell?
They interact with APCs and detect pathogenic peptides on MHCs they then become cytotoxic T-cells
What killing mechanisms do cytotoxic T-cells have?
They use:
- Perforin
- Granzymes
- Granulyson
What does perforin do?
Aids in delivering contents of granules into the cytoplasm
What are granzymes?
Serine proteases that when in the cytoplasm initiate apoptosis
What is Granulysin?
Antimicrobial
What is the development process of T-cells in the thymus? (For CD4 and CD8)
Double negative (1,2,3,4) and then double positive then to single positive. Leaves one receptor on the cells by its self.
Where do T-cells mature?
In the thymus
How do T-cells recognise infected cells?
Through MHC molecules on antigen presenting cells recognised by the TCR.
