T cells Flashcards
What are T cells?
They are thymus selected lymphocytes that mature in the thymus. They are generated in the bone marrow but migrate and mature here.
What are T cells required for?
Cell mediated immunity. They evoke responses by mobilising and activating other cell types or attaching to and recognising and killing virally infected cells. They help B cells become activated and produce antibodies.
What do T cells respond to?
Antigenic fragments that are presented by MHC molecules on APCs.
In terms of recognising foreign material, how do B cells and T cells differ?
T cells can only recognise antigenic fragments - the antigen needs to be broken up.
What are the different types of T cells?
T Helper cells (1 and 2) and cytotoxic T cells.
What is the main physical characteristic of T helper cells?
They contain CD4 surface protein. This has a physiological function but is generally used as a marker.
What cell surface receptor do all T cells have?
CD3.
What is CD25?
The interleukin receptor which is a growth factor for T cells. If T cells have CD25, they are active T cells.
What is the function of Th1 cells and what do they produce?
Activate macrophages and cytotoxic T cells and produce large amounts of IFNgamma/TNFalpha.
What is the function of Th2 cells and what do they produce?
They provide costimulatory help to B cells and secrete IL-4/5/10 to stimulate these B cells.
What is the main anti-inflammatory cytokine?
IL-10.
What causes chronic inflammation?
Overactivation of the B cells.
What are methods to treat chronic inflammation?
B cell therapies - targeting the B cells in chronic inflammation.
What cell surface receptor do cytotoxic T cells have?
CD8+.
What is the function of cytotoxic T cells?
They recognise antigenic fragments presented on class I MHC and kill infected cells.
What are the 4 types of antigen presenting cell?
Macrophages, neutrophils, B cells and dendritic cells.
What surface proteins are found on T regulatory cells?
CD4, CD2 - only expressed on activated T cells.
How are T regulatory cells linked to T helper cells?
They are a subpopulation of active T helper cells, but instead of stimulating the immune response they dampen it down.
What is one of the key functions of T regulatory cells?
They suppress the activation of self-reactive T cells to stop us reacting to our own tissue.
What is Foxp3?
A transcription factor that is critical for immunosuppressive function. Mutation can lead to autoimmunity.
What cytokines do T regulatory cells secrete?
Anti-inflammatory cytokines such as IL-10. TGFbeta.
What structure does the T cell receptor have similarities with?
Antibodies.
What is the structure of the T cell receptor?
It is made up of alpha and beta membrane bound chains with immunoglobulin domains.
What is the T cell receptor associated with in the membrane?
CD3 chain.
