T-Cell Activation Flashcards
Processes: 1. antigen recognition/ costimulation a. antigen recognition/ TCR signaling i. CD3: ITAM signal transduction ii. epsilon- ITAM signal transduction iii. CD4/ CD80 Lkc signal transudction b. costimulators- i. CD28 receptor on Tcells ii. CD40 L iii. co-inhibitors: CTLA-4 and PD-1 c. adhesion molecules- 2. Pathways 1. PLCA1- calcium 2. PLCA- DAG 3. GTP/ RAS 4. PI-3 Kinases 3. Differentiation
cell mediated immunity
defense against infections by itnracellular microbes
clonal expansion
duplication of lymphocytes with antigen-specific receptors
differentiation
conversion of naive t cells into a mature population of effector T cels
molecule: CD4
on: Helper T Cells
wh: co-receptor
f(x): bind to APCs at a site separate from the peptide binding cleft of the MHC I
molecule: CD8
on: cytotoxic T Cells
wh: co-receptor
f(x): binds to APCs at a site separate from the peptide binding cleft of MHC II
molecule: CD3 proteins
on: T cells
wh: cell surface molecule, associated with TCR
f(x): signal transduction by TCR complex
*works with the epsilon chain
molecule: CD4
on: Helper T Cells
wh: costimulatory molecules that bind to MHCII
f(x): necessary in addition to antigen binding to the TCR in order to initiate activation signaling.
may require cross-presentation
CD8
on: Cytotoxic T Cells
wh:costimulatory molecules that bind to MHCI
f(x):necessary in addition to antigen binding to the TCR in order to initiate activation signaling.
CD28
on: T cells
wh: a receptor for costimulators
f(x): binds to B7-1 and B7-2 which are expressed in higher numbers on activated APCs
CTLA-4
on: T Cells
wh: inhibitory co-stimulator
f(x): inihibitory molecule for CD28 like proteins. mutations may contribute to susceptibility to diseases like Graves and Type I diabetes
LFA-1
on: T Cells
wh: cell adhesion receptor (integrin)
f(x): binds to a ligands on APCs (ICAM-1) and helps with processes like infiltration and immunosynapse formation
VLA-4
on:: T Cells
wh: cell adhesion molecule (integrin)
f(x): binds to VCAM-1, a ligand expressed on endothelial cells. important for initiating rolling and infiltration
TCR complex
on: T Cells
wh: TCR, epsilon chain, and CD3 protein
f(x): to initated signaling through Lck tyrosine kinase and ITAMs
superantigens
antigens that induce excessive inflammatory release of cytokines
ICAM-1
on: APCs
wh: cell adhesion ligand
f(x): a ligand on APCs that is captured by the cytotoxic T cell receptor LFA-1
VCAM-1
on: endothelial cells
wh: cell adhesion molecule, ligand
f(x): binds to the VLA-4 receptor on lymphocytes and promotes adhesion
B7-1/B7-2
f(x): an APC costimulator for T Cells
express by: APCs
wh: act as ligands and bind to CD28 receptor expressed constitutively on T cells. Co-stimulation is necessary for activation
CD40L
on: a Tcell costimulator for APCs
cells: T Cells
f(x): expressed by activated T-cells, binds to CD40 and makes APCs better at secreting cytokines and other activating factors
CD40
on: an APC costimulator receptor for Tcell ligand
cells: APC
f(x): binds to CD40, a molecule that is expressed on T-cells at a higher rate when they are activated. CD40 signaling favors greater production of cytokines
adjuvants
costimulatory molecules that are added to vaccines, mainly to promote activity of APCs, examples include CD40 and B7
immunological synapse
f(x): facilitates proper signaling, possibly other activities like termination of immune response
center: CD4/CD8 receptors and CD28
peripheral ring: integrins
Lck
wh: tyrosine kinase
on: T Cells, intrallcelllar part of CD4 or CD8 costimulator
f(x): initiates TCR mediated signaling by phoshorylating residues on the ITAM regions of CD3 and epsilon proteins
ITAMs
wh: regions of CD3 and the Epsilon chain
on: expressed in T Cells, intrallceular
f(x): they are phosphorylated by the Lck tyrosine kinase and serve as a scaffold for ZAP-70
ZAP-70
on: T Cells
wh: helps initiate TCR mediated signaling
f(x): docks on phosphorylated ITAM regions of CD3 and the epsilon chain, the protein itself is phosphorylated by Lck tyrosine kinase and goes on to phosphorylated adaptor proteins in diverse pathways
