Flashcards in T Cell Immunity Deck (24):
What are the two types of T cell receptors?
*T-cell will have one or the other, not both
What is the most common type of T cell receptor?
What are CD4 and CD8 with respect to T cell receptors?
What do alpha-beta receptors recognize?
BOTH the presented peptide and the MHC molecule
How do T-cell receptors signal the T cell nucleus?
-TCRs cluster together
-CD3 recruits kinase enzymes to activate nucleus & proliferation
What do CD8 and 4 do?
clip onto either MHC I (CD8) or MHC II (CD4)
=focus the attention of Th and CTL cells on the proper MHC molecule, stabilizes connection
-strengthen TCR signal to the nucleus
What acts as the costimulatory signal to activate naive T cells?
**on B cells and dendritic cells
What happens when CD40L on the Th cell binds to the CD40 receptor on the dendritic cell?
-dendritic expression of MHC and B7 will be increased
-dendritic cell's lifespan is also extended
What do helper T cells do once they are activated?
-parts ways with APC
-produce large amounts of IL-2
What is a brief sequence of T cell activation?
-Adhesion molecules mediate weak binding between Th and APC
-TCR’s engage their cognate antigen presented by APC
-Receptor engagement strengthens the adhesion
-Upregulates CD40L expression on the Th cell
-CD40L binds to CD40 on the APC
-Stimulates expression of MHC and co-stimulatory molecules on APC
-When activation is complete the Th cell proliferates
-This proliferation produces clones of helper T cells which recognize the invader
How do helper T cells enhance the action of Cytotoxic T Lymphocytes?
-Help CTLs kill efficiently
-Th also help CTL's become long-lived
-helps CTL's generate memory T cells
-Provide IL-2 needed for CTL's to proliferate (controls strength of response)
What interleukin is produced by activated dendritic cells once they reach a lymph node?
What does IL-2 from T helper cells do?
-recharges natural killer cells
-stimulates growth of Cytotoxic T lymphocytes, NK cells, and Th1 cells
What do Th1 cytokines do?
-instruct the innate and adaptive systems to produces cells and antibodies against both viruses and bacteria
-IFN-gamma tells B cells to switch to IgG3
Which cytokines are produced by Th2 cells?
What does IL-4 do?
-stimulates production of Th cells
-stimulates B cell growth
-Influences production of IgE antibodies (good against parasites)
What does IL-5 do?
-encourages B cells to produce IgA
* useful in protecting GI tract
What does IL-13 do?
-stimulates production of mucus in GI system
*protects against pathogen invasion
What do Th0 cells do?
-remain "unbiased" when first activated, retaining the ability to produce a wide range of cytokines
Do cytokines act locally or systemically?
What produces perforin and what does it do?
-produced by cytotoxic T cells
-binds to cell membranes and drills holes in them
What does a cytotoxic T cell use to kill its foes?
-Granzyme B (triggers Apoptosis)
-FasL (binds Fas, triggers Apoptosis)
What cytokines are produced by Th1 cells?