T Cell Subset And Function Flashcards
The main cell type that causes activation of naive T cell is
Dendritic cell
What type of blood vessel do T cells pass through before they enter the lymph nodes
High endothelial venules
Which receptors on T cells promotes movement into lymph nodes
CCR7 and L selectin
How do T cells leave the lymph nodes
Down regulation of CCR7 on T cells once they enter the lymph nodes allowing them to exit
S1PR1 on T cell binds to S1P molecule and follow S1P gradient causing it to leave the lymph nodes to travel towards the site on infection
What causes bond between t cell and APC to prolong
LFA 1 on T cell binds to ICAM 1 on APC weakly initially
Complimentary fit of MHC with TCR causes conformational change on LFA1 causing it to bind stronger to ICAM 1 resulting in prolonged cell-cell contact
Signals required for T cell activation and proliferation
Complimentary binding of MHC to TCR results in signal 1
Binding of B7 on APC to CD28 on T cell causes costimulatory signal which is signal 2
Receptors that regulate action of T cells
CD28 on T cell binds to B7 of APC to produce stimulatory signal
CTLA 4 on T cell binds to B7 of APC to produce inhibitory signal
PD1 receptor on T cell binding leads to inhibitory signal
Downstream signalling leading to t cell activation
CD4/8 is associated intracellularly with LCK
Upon activation and co-stimulatory signal, LCK phosphorylizes ITAM and ZAP70 which leads to further downstream signalling resulting in NFAT, NFKB, AP-1 activation which causes increased protein synthesis
What is another name for IL2?
What is the 2 types of receptors for this cytokine and where is it found?
T cell growth factor
Moderate affinity IL2 receptor, Beta and gamma sub unit found in Naive T cell
High affinity IL2 receptor , Alpha, Beta and Gamma found in Effector T cell
Other markers apart from IL2 for T cell proliferation
CD 69 and CD40
Cd number of B7-1 and B7-2
CD80 and CD86
Full proliferation and differentiation of naive CD8 T cell requires
Complimentary binding of CD8 TCR to MHC1 of APC
Co-stimulatory signal
T helper cell - produce IL2 and activate APC to produce CD40 to further stimulate T cell differentiation
T cell subsets and the cytokines produced
Th1 = IFN gamma Th2 = IL4, IL5, IL13 T17 = IL17, IL22
Production of IL12 by APC causes what
Activation of NK cells to release IFN gamma
IL12 and IFN gamma causes T helper cell to become Th1
What are the effects of Th1 cell
Produce IFN gamma
Interact with macrophages via CD40 to make them highly microbicidal
Mainly combats bacteria and parasite
How T cell subset affects other T cell subsets
Th2 secretes TGF Beta and IL10 which inhibits activation and growth of Th1
Th1 secretes IFN gamma which inhibits Th2 proliferation
What are the 2 category of memory T cells
Central memory T cell = remains in lymph node
Effector memory T cell = remains in peripheral tissue
Cytotoxic contents used by CD8 T cells
- Perforin = forms pore in target membrane
- Granzyme = cause apoptosis
- Granulysin = cause apoptosis
Features of macrophages activated by CD4 t cells
- Increased lysosomal enzymes
- Increased ROS
- Promotes Inflammation
- Recruit more leukocyte
What are the effects of Th2 cells
IL4 stimulate B cell to produce IgE
IL5 causes Eosinophil activation against Helminth
IL4,13 stimulate B cell to produce intestinal secretion and peristalisis
IL4, 13 also causes activation of macrophage to enhance tissue repair
What are the 2 types of macrophages and their functions
M1 = activated by Th1, pro inflammatory, carries out phagocytosis of bacteria and parasite M2 = activated by Th2, carries out wound repair
Th17 cell function
Produce IL17 and IL22
IL17 causes inflammation, neutrophil response, antimicrobial peptide synthesis and increased barrier integrety
What is the only type of inhibitory T cell subset
T regulatory cells
What is the function of Tfh
Antibody production for all types of infection
