T Cells Flashcards
What is an antigen presenting cell
Links adaptive and innate immune systems
Present antigens to t cells through MHC (dendritic cells)
What are T Cells
Lymphocytes specific for a particular antigen.
What do T cells proliferate into
Cytokines and Cytotoxic molecules
Where are T cells located
In lymph nodes - this is also where they are activated
Describe MHC 1 processing for endogenous antigens
Antigenic protein degraded in cytoplasm
Loaded on MHC 1 in ER (Endoplasmic reticulum)
What is an example of endogenous antigens
Viral proteins produced during replication. Intracellular bacteria proteins
Describe MHC 2 processing for exogenous antigens
Breakdown and loading in phagolysosome onto MHC 2
What is an example of exogenous antigens
Fungi
Bacteria
Parasites
Describe the life cycle/development of T cells
Produced in bone marrow develops receptors in the thymus and activated by MHC
What does the T cell do in the thymus
Develops T cell receptors (TCR) - gene rearrangement.
Allows to recognise antigens and removes ability to recognise itself as one
How are TCR’s built
Gene rearrangement - random process that creates different receptors that respond to one antigen. This creates diversity (so immune system can recognise all pathogens)
CD4 T cells
Recognises MHC 2 - helps CD8 become cytotoxic and helps b cells make antigens - By producing Cytokines (chemical messengers)
CD8 T cell
Recognises MHC 1 - Develops into Cytotoxic T lymphocyte (CTL) with help from CD4 - Sends out kill message to infected cells
Where are MHC 1 and MHC 2 receptors present
MHC 1 present on all cells with a nucleus
MHC 2 present on all phagocytic cells
What are memory T cells
Stay in body for long periods of time. Are quicker to activate than naïve cells
