T Cell Mediated Immunity Flashcards
T cells that encounter antigen proliferate into ____ cells
Effector
CD4+ T cells recognize ________
HLA Class II
CD8+ T cells recognize _________
HLA Class I
TCR/HLA antigen recognition changes ____ conformation on T cells from low to high affinity
Integrins
During co-stimulation, what cell constituvely expresses CD40 and CD28?
APCs constitutively express CD40
T cells constitutively express CD28
During co-stimulation, what cells increase CD40L and CD80? Note which cell/receptor these bind to.
CD40L is increased on T cells
CD80 (B7) is increased on APCs
CD40L (T cells) binds to CD40 (APCs)
CD80 (APCs) binds to CD28 (T cells)
What is the signaling chain on T cells? How does it make an intracellular signal.
Zeta
ITAMS- Immunoreceptor Tyrosine Based Action Motifs
Describe a situation of Anergy (unresponsiveness) during T cell response.
T cells recognize antigen without binding of co-stimulatory ligands or cytokine support will not become activated
Anergy= Anergic/Tolerant
What is the function of IL-2 in terms of T cell function? What cell releases IL-2?
T cell proliferation and T cell survival
Activated T cells release IL-2
What is the function of IFN-gamma? What cells release this?
Activation of Macrophages
CD4+ and CD8+ T cells and NK cells
What is the function of IL4? What cells release this?
B cells switching to IgE
Mast cells
CD4+ T cells
What is the function of IL5?
Activation of eosinophils
What is the function of IL17?
Stimulation of acute inflammation
What are the functions of TGF-beta and IL10?
Inhibition of T cell activation
Differentiation of regulatory T cells
How are T cells trapped into lymph nodes?
CD69 expression leads to the sequestering of the S1PR1 receptor and therefore traps the T cell in the lymph node
S1PR1=Sphingosine 1 Phosphate Receptor 1
*Note that 5 days after the arrival of the antigen, S1PR1 is re-expressed and therefore allows the T cell to emigrate from the lymph node
What cell releases IFN-gamma and IL12 and what are the functions of these cytokines?
Th1 releases these cytokines
Leads to the activation of Macrophages
What cell releases IL4/IL5/IL13 and what are the functions of these cells?
Th2 releases these cytokines
Leads to the activation of Eosinophils B cell class switching to IgE
What cell releases IL-17 and IL-22? What is the function of these cytokines?
Th17
Neutrophil recruitment and activation
What cell releases IL21? What is the function of this cytokine?
Thf cells release these cytokines
Leads to antibody production on B cells
What receptors do Treg cells constitutively express?
CTLA4 and CD25
what transcription factor do Treg cells release?
FOXp3
What is the major difference between effector T cells and resting naive T cells?
An effector T cell is able to respond to a specific antigen without the need for co-stimulation via B7 (CD80)-CD28 interaction
What transcription factor do Th1 cells release?
Tbet
During Classical Activation of Macrophages, what cytokine activates macrophages against intracellular microbes?
IFN-gamma, which activates B cells to stimulate class switching and complement binding. Th1 releases IFN-gamma
This stimulates class II HLA and B7 (CD80) expression
What transcription factor does Th2 release?
GATA3
During Alternative Activation of Macrophages, what cytokine activates macrophages for tissue repair?
IL4 and IL13 from Th2
What transcription factor does Th17 release?
RORyt
What are the 2 killing mechanisms of Cytotoxic T Lymphocyte Function?
Cytotoxins are delivered directly onto the surface of the infected target cell.
Granular proteins:
-Granzymes- activates caspases
-Perforin- necessary for delivery of granzymes
Fas(CD95) and FasL: simulates of apoptotic pathways
What are the 5 cells that are involved in Antibody Dependent Cell Mediated Cytotoxicity (ADCC)? What 2 antibodies are used in this?
NK cells Macrophages Monocytes Neutrophils Eosinophils
Target recognition through IgG or IgE
What cell constitutively expresses CD28? What is the function of CD28?
T cells constitutively express CD28
Involved in co-stimulation of naive T cells
Development of Treg cells
What cell expresses CTLA-4? What is the function of CTLA-4?
T cells increase expression of CTLA-4
Negative regulation of immune responses
Self-tolerance
What cell expresses ICOS? What are the 2 functions of ICOS?
T cells increase expression of ICOS
Co-stimulation of effector and regulatory T cells
Generation of Follicular Helper T cells
What cell expresses PD-1? What is the function of PD-1 on T cells?
T cells
B cells
Negative regulation of T cells- leads to T cell exhaustion causing no cytokine secretion and reduced proliferation.
What is the mechanism of Mycobacterium?
Inhibition of the formation of the phagolysosome
What is the mechanism of the Herpes Simplex Virus (HSV)?
Inhibition of antigen presentation by the HSV peptide interfering with the TAP transporter
What is the mechanism of the cytomegalovirus (CMV)?
Inhibition of antigen presentation by inhibiting the removal of class I MHC molecules from the ER.
What are the 2 mechanisms of the Epstein Barr virus (EBV)?
Inhibition of antigen presentation: Inhibition of proteasomal activity from degrading the viral antigens
Production of IL10, which leads to the inhibition of macrophage and dendritic cell activation
What is the mechanism of the pox virus?
Inhibiting the activation of effector cells by blocking soluble cytokines from being released.
Soluble Cytokines- IL1 and IFN-y
What 2 cytokine signals do Memory T cells require in order to survive?
IL7 and IL15
