T cell activation Flashcards
what happens between the T cell and dendritic cell?
there is cognate interaction as binding occurs
On the T cell receptor what does the cytoplasmic tail interact with?
signalling molecules upon recognition
what happens when the T cell recognises the antigen / MHC upon recognition ?
T cell and antigen-presenting cell form interaction . The TCR transmits signals and T cell becomes activated.
what’s the 3 things that happens once the T cell becomes activated ?
proliferation
effector function
polarisation
explain proliferation
As there is huge diversity means that antigen-specific T cells are rare so therefore there activated T cells are ‘useful’ so need to proliferate to generate effective immune response as more are produced. The self reactive lymphocytes are removed and the mature T lymphocyte remains.
describe effector functions
Once the T lymphocyte matures it can differentiate into either a
– CD4+ T cells – ‘helper’ function
– CD8+ T cells – ‘killer’ function
how do the CD8 T cells carry out their effector functions ?
by killing the infected target cell
how does the CD4 T cell carry out their effector function ?
by ‘helping’ the B cells to make antibodies
describe polarisation ?
cells can ‘polarize’ into T1 and T2 effector cell types in response to distinct cytokines.
what does the Th1 cell secreate ?
IFNγ and TNF and activates this macrophage functions
what does Th2 secrete ?
IL-4 , IL-5 and IL-10 and ‘helps’ antibody production from B plasma cell. involved with allergic responses
what are the CD86 and CD80 ?
co stimulatory molecules that are produced from the APC.
what dictates what cytokines are released ?
the co stimulatory molecules produced from the APC
what activates the APC to release the co stimulatory molecules ?
the PAMP’s binding to the PRR’s
what happens when Th1 are produced ?
the Th2 production is shut down and vice versa
what hapens if this cross communication doesn’t occur ?
you can get allergies or septic shock
describe Th1 cells ?
The Th1 cell normally binds to macrophages by IFN-y and this kills intracellular bacteria
describe Th2 cells ?
The Th2 cells release cytokines IL 4 , IL 5 which activate bone marrow to produce antibodies. The IL 13 released affects the goblet cells and mucus is released. From these cells eosinophils , mast cells and basophils are produced. Normally associated with Helminth parasites.
describe Th17 cells ?
These cells release IL 17 which affects stromal cells to release G-CSF and cytokines. IL 22 is released and this causes antimicrobial peptides. This results in neutrophils being released to break down extracellular bacteria and fungi.
describe Tfh cells ?
These are follicles of the T cells that have no MHC. They produce IL 21 , they also activate the B cell and cause IgM ( antibody) to be released. These then cause the production of other antibodies that can target all types of microbes.
describe Treg ?
These cells are regulatory, and they calm down the immune response by inhibiting the dendritic cells. Therefore, there is no APC cells activating the cd4+.
what is the differentiation of CD4 T cells controlled by ?
their interaction with the antigen presenting cell and the local cytokines.
what can result if there is an overactivity of Treg cells ?
lead to no immunity and death
describe activation of T cell ?
this is the binding of the MHC , TCR and peptide
describe survival of T cell ?
this is when the co stimulatory molecules arrive.
describe differentiation of T cells ?
this is when the cytokines interact and effector function
why are memory cells important in the use of vaccines ?
they reduce the primary response so that the immune response occurs faster and more efficiently.
