Lecture 5 - T cell activation (post thymus) Flashcards
following their exit from the thymus, t cells enter the lymphatic system through what?
high endothelial venules
what do inactivated T cells leave the circulation via?
cortical sinuses
which molecules help T cells to make contact with APCs?
where are these molecules expressed?
cell adhesion molecules
on the surface of T cells
which molecule, expressed on T cells, do CAMs interact with to mediate T cell-APC contact?
LFA-1
if the TCR recognises the antigen, a signal is sent from which complex?
what does the signal tell the t-cell do?
signal sent from the TCR complex
signal tells the T cell to divide into an effector cell, exit the lymph nodes and move to site of infection to elicit a response
how many signals needed for T cell activation?
3
which chain of the TCR does signal 1 of activation involve?
CD3 zeta chain
what creates signal 1 in T cell activation?
naiive T cells receiving signal from TCR-peptide contact
in signal 2 of T cell activation, co-stimulatory molecules bind to what on naiive T cells?
CD28
in signal 3 of T cell activation, APCs release cytokines which bind to what on naiive T cells?
upregulated receptors
once all 3 signals are given, T cells do what? Which two molecules do they express?
T cells proliferate and express CTLA-4 and ICOS
ICOS binds to …… on APC to induce the secretion of …… by T cells?
ICOS ligand / ICOSL
cytokines
what does CTLA-4 bind to on APC more avidly than CD28 does?
B7.1 and B7.2
what type of signal does CTLA-4 deliver to activated T cells?
negative signal
CTLA-4 mutations induce an unwanted autoimmune response. Name 3 diseases in which this is part of the pathology. (hint- 2 are cancers)
type 1 diabetes, melanoma and renal carcinoma
CAM molecules mediate which 3 interactions?
T cell and APC interactions
naiive T cell and HEV interactions
T cell and target cell interactions
what do the 2 co-stimulatory molecules bind to?
CD28
which signal number do co-stimulatory molecules provide in T cell activation?
signal 2
what are the 2 co-stimulatory molecules?
B7.1, B7.2
B7.1 is associated with which CD molecule?
CD80
B7.2 is associated with which CD molecule?
CD86
which interleukin is a key cytokine for T cell survival and proliferation?
IL-2
when activated, T cells express a high affinity receptor for which cytokine?
IL-2
which cytokine, associated with T cell activation, is a target for the immunosuppressive drug cyclosporin?
IL-2
what are the 3 cell types which present antigens?
dendritic cells, B cells, and macrophages
what is the function of myeloid dendritic cells?
activate naiive T cells
which toll like receptors do plasmacytoid dendritic cells express?
7 and 9
what type of pathogenic infection are plasmacytoid dendritic cells responsible for dealing with?
viral infection
which two types of interferons do plasmacytoid dendritic cells secrete?
kappa and beta
which MHC class do macrophages express?
which co-stimulatory molecule do macrophages associate with?
class 2
B7
what do macrophages secrete?
inflammatory cytokines
signal 2 is given to T cells by co-stimulatory molecules bind to CD28 on T cells.
how can signal 2 be given in an alternative way to T cells?
antigen binding to B cell receptors which upregulates B7 (a co-stimulatory molecule which delivers signal 2 to T cells)
cross presentation involves the uptake of what by dendritic cells?
exogenous antigens
in cross presentation, exogenous antigens are presented on which molecule?
MHC class 1
what does cross presentation of antigens allow dendritic cells to do?
activate naiive CD8+ T cells - they can then kill other cells
what do CD8+ T cells do in simple terms?
kill other cells
what do CD4+ T cells do in simple terms?
secrete cytokines
what are the 3 subgroups of T cell (3 stages in a T cell’s life)?
hint- starts with naiive T cells
naiive
effector
memory
