Lecture 25: Lymphocyte Activation by Antigen Receptor & Fc Receptor Signalling Flashcards
what are 5 keys to effective T cell response?
- diversity/adapt
- Pathogen removal
- polarity (produce cytokines)
- memory
- regulation
what is the role of signal 3 cytokines?
drive naive CD4+ T cells to effector CD4+ T cells
cytokines secreted by CD4+ effector T cells can act as signal 3 for ___ cells
CD8+
T helper subsets are generally named for the major cytokines they ___
produce
after activation, Th cells commit to a subset through activation of a specific _____
transcription factor (master gene regulator)
t/f each effector T helper cell subset is characterized by a distinct polarizing cytokines that induce expression of a master gene regulator that regulates expression of signature effector cytokines involved in protective immune responses
t
the suite of polarizing cytokines and therefore the type of Th subset created is determined by what 4 things?
- cell type altered
- nature of pathogen
- pattern recognition receptor stimulated by PAMPs
- tissue context
what is the function of helper T cell subsets?
guides the generation of an optimal response to a given pathogen
t/f T helper subsets can cross-regulate one another
t
IFN-y promotes Th__ and suppresses Th__
Th1; Th2
IL-4 promotes Th__ and suppresses Th __
Th2 and Th1
t/f Th17 and Treg cells cross-regulate each other
t
Th1 and Th2 cross-regulation is mediated by ___ and ____
IFN-y and IL-4
IL-4 ___ (inhibits/increases) IL-12 secretion by APCs
inhibits
Th17 and Treg cross-regulation is mediated by the combination of ___ and ___
IL-6 and TGFB
___ and ___ inhibits FoxP3 expression
IL-6 TGFB
high levels of TGFB alone promotes ___ expression
Fox P3
IL-6 induces protective Th17 cells in the presence of ____
TGFB
when a pathogen is cleared, ___ drops and ____ dominates to induce Treg cells
IL-6; TGFB
the expression of Bcl-6 has what effect on T-Bet, GATA3 and RORyt expression?
inhibits
what is the effect of IL-2 on the development of Tfh cells?
inhibits
what is the function of T follicular helper T cells?
provide cognate help to B cells and enhance switching to different classes of antibody
Tfh cells express high levels of ___ and ___
CD40L and CXCR5
what are the functions of the CD40L and CXCR5 found on T follicular helper cells?
CD40L: needed to provide help to B cells
CXCR5: attracts Tfh cells to B cell follicles
cell-mediated immune responses eliminate what types of cells?
cells that have become malignant, of infected
the cell-mediated immune response consists of antigen-specific effector cells, such as ____
CD8+ T cells, CD4+ T helper (Th1) cells
the antigen-specific effector cells of the cell-mediated immune response work togther with what other cell types?
macrophages, NKT cells, NK cells, and non-specific effector cells (macrophages, neutrophils, and eosinophils)
what is the function of macrophages in cell-mediated immunity?
mediate delayed-type hypersensitivity (DTH) reactions
cell mediated immunity requires cytokines made by what cell types (5)?
- Th1
- NK
- NKT
- dendritic cells
- macrophages
NKT cells participate in both ___ and ___ immune responses
innate and adaptive
NKT cells develop in the ____ where they undergo ____ rearrangement
thymus, TCR gene
most NKT cells express what type of TCR?
invariant aB TCR
what do the TCRs of NKT cells recognize?
glycolipid antigens presented by nonpolymorphic CD1 on APC and epithelial cells
t/f NK cells are CD4+, CD8+ or CD4- CD8- cells
t
NKT cells express proteins typical of ___ cells
NK
do NKT cells form memory cells?
no
what are the 2 main functions of NKT cells?
- as helper cells (secreting cytokines that shape response)
- as cytotoxic cells that kill by Fas interactions
how do NKT cells act as cytotoxin cells?
by Fas Fas ligand interactions
NKT cells function as a ____(delayed/rapid) response to provide ____(late/early) help (Th1 and Th2 cytokines) against invading pathogens
rapid, early
NK cells use ___ receptors and the ____ model to provide an early cytotoxic response
NK; balanced signals
how do NK cells impact adaptive immunity?
by promoting Th1 differentiation, inhibiting Th2 development and driving CD8+ induction by their production of IFN-y
t/f NK cells are necessary for optimal CTL function
t
NK cells are constitutively active due to ___, ___ and ___ expression
granzyme, perforin and Fas ligand
NK, neutrophils, eosinophils, monocytes, and macrophages express ___ receptors for the Fc regions of ____, allowing ADCC (antibody-dependent cell-mediated cytotoxicity
CD16; IgG
what are ADCC (antibody-dependent cell-mediated cytotoxicity) reactions?
nonspecific killer cells are directed to kill IgG-coated target cells
when NK cells are activated through their CD16 receptors, what do they release? What pathway do they use to kill?
the contents of their cytoplasmic granules (granzymes and perforin); fas pathway
neutrophils, eosinophils and macrophages activated through their Fc regions release ___ . Do they become more or less metabolically active?
the lytic contents of their lysosomes; more
activated NK cells, monocytes and macrophages also release ____ which kills certain target cells
TNF alpha
a small population of double negative T cells in the skin, intestines, and pulmonary system express the ___-type TCR that is not restricted in activity by self MHC
delta gamma
the delta gamma TCR cells are thought to act as first line defense against cancer and infection based on their ability to respond directly to _____ antigens and mediate cytotoxicity
heat shock
what are thymic (naturally occuring) CD4CD25+ T reg cells?
cells genrated in the thymus that move to the periphery to regulate activity of other T cells
