#3 - Life of a T Cell: Responding to an Infection Flashcards
what type of cell produces the third signal for T cell activation?
antigen presenting cell
what’s the difference between NK cells and NK T cells?
NK T cells (also known as iNK T cells) have TCRs
what’s the difference between the secretion of cytokines from CD4 and NK T cells?
NK T cells secrete cytokines very rapidly, usually within minutes or hours of stimulation
what is the principal role of dendritic cells?
to respond to pathogens with the release of cytokines
what determines the type of signal three that is secreted?
the PRR on the APC that reacts to the pathogen
what role do Th17 cells play?
important in fungal and viral infections
what are all the relevant cytokines and TF’s for Th17?
IL-1, IL-6 and TGF-beta activate Th17 cells, RORgamma-t is the necessary transcription factor, IL-17 is the cytokine that it produces
what role do Treg cells play?
they down regulate auto-reactive T cell species
what are all the relevant cytokines and TF’s for Treg?
the transcription factor is Foxp3, cytokines to activate Treg cells are unknown, it produces IL-6 and IL-10
what role do Tfh cells play?
they help with B cell activation in germinal centers
what are the relevant cytokines and TF’s for Tfh?
IL-6 and IL-21; TF is bcl6; it produces IL-21
what is the parasite that causes toxoplasma infection?
T. gondii
where are the DC’s that produce the cytokines for Th1 cells, during a toxoplasma infection?
in the lamina propria of the gut
what kind of cytokine does the Th1 Cell produce in response to signal III
gamma-interferon
what are the functions of the Th2 cells?
the secretion of IL-5 and IL-13 helps B cells with isotype switching, specifically toward IgE secreting B cells
what are the main functions of Th17 cells?
protection against bacterial and fungal infections, esp. in skin and mucosal areas of the body
what are the functions of the Treg cells?
prevent CD4 cells from becoming activated in response to self-peptides or self-HLA
what are the functions of CD8 T cells? how do they perform this role?
they are cytotoxic killer cells, they release granzyme and perforin
what intracellular signal triggers the release of the cytotoxic granules?
calcium
when activated by T cells, what do macrophages do?
upregulation of surface proteins (HLA II) related to killing, and respiratory burst to produce ROS
what complex generates ROS?
NADPH
what causes chronic granulomatous disease?
malfunctions in the NADPH, ROS producing system
what is the product of the TB infection called?
caseous granuloma
what causes caseous granulomas?
Th1 and Macrophages walling off the area of infection
what cytokine causes septic shock?
TNF
what are the two functions of IFN (gamma)?
creation of anti-viral healthy cells and the killing of infected cells
what are the two receptors on the influenza virus that are used for identification?
Hemagluttinin and Neuraminidase
what type of virus is influenza?
orthomyxoviridae
what intermediate do all viral RNA’s go through?
dsRNA
how does influenza breach the epithelial barrier?
they enter the epithelium and cause the release of TNF and IL1 that cause vasodilation
about how long does the T cell response to influenza take to gather enough CD8 cells to make a difference?
7-10 days
what are the main regulators of the contraction of the T cell response?
reduction in IL-2
up-regulation of Fas
expression of inhibitory molecules
differentiation of activated T cells into memory cells
what are the three main inhibitory molecules to the activity of T cells?
CTLA-4, PD-1 and Fas
how does CTLA-4 inhibit T cell activation?
competes with CD28, has higher affinity for CD80/86 than CD28
how does Fas down regulate T cells?
Fas-l binding to Fas causes apoptosis
