Immunology 5 Flashcards
IL-2 is a major ?
T cell and B cell growth factor
once the naive T cell is activated, it begins to synthesize ? and the high-affinity form of the ?
IL-2 and IL-2 receptor
IL-2 binding to the Th IL-2 receptor acts in an ?
autocrine fashion
the binding of IL-2 to the receptor on the T cell, activates the Th cell and causes it to ?
enter the cell cycle and avoid apoptosis
synthesis of both IL-2 and the high affinity IL2R is induced after?
CD28-CD80/86 binding and recognition of antigen
antigen recognition in absence of co-stimulation causes ?
T-cell anergy and cannot produce IL-2
T or F: CD4+ helper T-lymphocytes (Th) kill pathogens or other “foreign-looking” entities directly
false, they never kill pathogens directly
how do helper T-cells aid immunity?
- activate or inhibit other cells through direct contact (CD8+ cytotoxic T cells, B-cells, macrophages
- activate other cells through secretion of cytokines
Th cells will differentiate after they are activated so that they “help” in a specific way - this is known as ?
T-cell polarization
T helper cells become ? after they are activated
polarized
Polarization = ? -> the Th secretes ? that mediate distinct effector cell functions
specialized Th phenotype
a “profile” of cytokines
Th type is determined by the ?
environment it is found in
the types of cytokines that are present in high concentrations in the immediate vicinity of the newly-activated Th – these are known as ?
polarizing cytokines
what are the polarizing cytokines of Th1
IL-12 and IL-18
IL-12 and IL-18 bind to their receptors on the Th cell -> activation/production of the ?
Th1 transcription factor
what is the Th1 transcription factor?
Tbet
what is the thing that polarizes the Th?
transcription factor
Tbet causes the Th to secrete ?
IFN-y
what is one of the principal effector actions of Th1 cells
macrophage activation
Macrophages require 2 signals for activation which are?
- IFN-y
- cell contact -> CD40-CD40L
Th cells usually first activated and polarized in?
secondary lymphatic tissue/organs (SLO)
Polarization type (Th1, Th2, Th17, Tfh, Treg) usually seems to be dependent on the ?
APC
Signals generated by a polarized Th cell tend to prevent other local Th cells from being polarized into a different type, this is known as ?
cross-regulation
what are the 3 major polarizing cytokines for Th17
IL-6, IL-23, TGF-b
Th17 effector cells produce?
IL-22 and IL-17
what does IL-22 and IL-17 do?
- Induce release of IL-6, IL-1, TNF-a, GM-CSF
- Cause release of chemokines that recruit neutrophils and macrophages
- Cause secretion of anti-microbial proteins from cells in inflamed tissue
what is the transcription factor that polarizes a TH17 cell?
ROR-yt
what is “Type 1 response”
Th1 and Th17
what are the main Th cell that aids full B-cell development in the SLOs
follicular Th cells
T or F: Tfh cells stay in the SLOs for the duration of their activation
True
We make “2 rounds” of antibodies when we experience an infection that our immune system has trouble clearing. The two rounds are:
Round 1 - lower-affinity antibodies, many epitopes
Round 2 - B-cells “reshuffle” their antibodies and the ones that are very high affinity are selected to reproduce in germinal centres
The “2 rounds” of B-cell antibody production is known as ? and is crucial – without ?, it does not happen
affinity maturation
Tfh
what is inhibitory to Tfh development
IL-2
what is the polarizing cytokines for Tfh cells
IL-12 and low amounts of IL-2
what is the transcription factor for Tfh
Bcl-6
Tfh interacts with a B-cell via TCR-HLA2 and two other new costimulator interactions:
- ICOSL (iCOS ligand) on B-cells interacts with iCOS on Tfh (stimulate cytokine production)
- CD40L (CD40 ligand) on Tfh interacts with CD40 on B-cells (stimulate antibody production)
what is the major Tfh effector cytokine
IL-21 (also produce IL-4)
Follicular helper T-cells differ from other polarized Th cells:
- They stay in the SLO, interacting continually and closely with B-cells
- They undergo two separate rounds of interactions with APCs
- When the B-cell/antibody response to the infection is concluded, Tfh cells often gain the ability to switch types later
The development of regulatory T-cells is unique in that their effector activities ? effector activities of other immune cells
down-regulate
They arise in environments where APCs present an antigen in a cytokine environment that is predominantly ?
“anti-inflammatory”
what is the inducing/polarizing cytokine of Treg cells?
TGF-b
what is the transcription factor that causes a Th to become a Treg
FoxP3
what are the effector functions of the Treg
○ Secretion of anti-inflammatory cytokines:
§ TGF-b, IL-10
○ Down-regulation of CD80/86 signaling by binding to Treg CTLA-4
- Soaking up and “stealing” Il-2 from other effector T-cell
