t cell activation Flashcards
what are the requirements for t cell activation?
Antigen presented as peptides
by APCs using MHC molecules
Co-stimulators on the APCs
Cytokines
what are co- stimulators
APCs express molecules that are required for t cell activation in addition to the antigen
what are co stimulators (2)
Co-stimulators are important molecules that help activate our immune system
what happens when you have an activated APC
increased expression of co stimulators and secretion of cytokines
what are b7 co stimulautors?
molecules found on immune cells that play a crucial role in activating T cells.
what do t helpers do?
T helper cells
co-ordinate the immune response
what does a non specifc defense lead to?
macrophage/ neutrophil activation/ leukocyte migration
what does humoral immunity lead to?
activation of B cells
what does cellular immunity lead to?
activation of t cytoxic cells
what is the role of naiive t cells
Naïve T cells differentiate into different types of T helper cells
what is naive t cells dependant on?
is dependent on the type of cytokine secreted by the APC also dependant on what other cells are there as well
what does Pro-inflammatory macrophages give rise to?
Tissue damage
what does Anti-inflammatory macrophages give rise to?
Tissue repair
what does the TREG cell do? 1/2
Immunosuppression by binding to B7 molecules on APCs
what does the TREG cell do? 2/2
inhibit activation of neutrophils
- promotes angiogenesis
summarise Cytotoxic T cell activation
APCs are usually dendritic cells
Antigens need to be presented on MHC I molecules
T helper cells aid in CTLs activation in 2 ways
T helper cells aid in CTLs activation in 2 ways.
what ways do they help?
T helper cells secrete IL-2 which helps to activate naïve CTLs cells
T cells enhance the ability of APCs to stimulate CTLs cells
what are CTLs cells?
identifying and destroying cells infected with pathogen
what are the steps in Cytotoxic T cell activation
antigen recognition
lymphocyte activation
clonal expansion
differentiation
effector functions
what are the 2 major types of MHC protein molecules?
Class I MHC molecules
Class II MHC molecules
what is a Class II MHC molecules
are restricted to cells of theimmune system- macrophages, dendritic cells and B cells
what is a Class I MHC molecules
present on everynucleated cellin an organisms
where are CLASS 1 MHC molecules located?
MHCI molecules present peptides to T Cytotoxic cells
where are CLASS 2 MHC molecules located?
MHCII molecules present peptides to T Helper cells
what do cytotoxic t cells also produce?
Cytotoxic T cells also produce INF-γ (aids in activation of macrophages)
describe memory t cells?
Specific for the antigen
Persist for years/lifetime
Respond more rapidly to specific antigen stimulation than naïve cells
what TCR also known as?
T cell receptors
each t cell has what?
number of TCRs (of a single specificity)
what cell is only required in antigen recoginstion?
Only the TCR
what is intergrin needed for?
adhesion
what is CD28, CD3, CD4, CD8 needed for?
signal transduction.
what is the structure like in a TCR ?
can bind only one antigen
recognise antigens displayed as short peptides
What are the main types of APCs
dendritic cells, macrophages, and B cells
what can TCRs recongise?
antigens displayed as short peptides on MHC molecules
t helper cells TCR recognise what?
recognise antigens displayed on MHC II molecules
t cytotoxic cell TCR recognise what?
recognise antigens displayed on MHC I molecules
what cells do t helper cells recognise?
CD4+ cells
what do t cytoxic cells recongise?
CD8+
CD4+ and CD8+ aid in what?
initiating signalling pathways within the cell
binding of antigen to a tcr results in what?
activates a number of signalling pathways in the cell which results in its differentiation, proliferation activation of other effector activities
