True or False
MHC class I & II are like T and B cell Recptors in that they undergo genetic rearrangement
What are 4 primary interactions that take place between the surface of an APC & CD4T
1) Peptide/MHC & TCR
2) MHC Class II and CD4
3)Co-Stimulator Pairs (B7 w/ CD28 & CD152, CD40, CD154)
4)Adhesion Molecules (CD54 w/ CD11a/CD18 & CD58 w/ CD2)
What are the characteristics of an Activated Dendritic Cell?
-Increase expression of B7 on Surface
-Increase expression of MHC class II molecules on the surface (or if infected w/ virus, MHC class I molecules)
-Synthesizes high levels of chemokines (pro-inflammatory cytokines)
What are the functions of Effector T cells?
-Helper T cells produce cytokines that affect many cells
-Cytotoxic T cells kill infected target cells.
This cell determines whether or not a developing T cell can bind too tightly to self-antigen in MHC pocket
Thymic Dendritic Cell
T cells have CD40L on surface, which interacts w/ CD40 on the surface of the B cell...
True or False
Coritcal Thymus Epithelial cells are involved in which form of selection for T-cells?
To what molecules do Superantigens bind?
Superantigens bind to MHC class II and to one or more Vbeta regions of TCR.
What is the Danger Hypothesis?
States that exposure to foreign antigen induces tissue damage that sends danger signals to provide the secodary signal necessary to generate activated T cells.
What does calnexin do?
Chaperone that binds to partially folded MHC class I and maintains conformation for Beta2-microglobulin to bind.
The peptide binding groove of MHC class II molecules have the capacity to bind to peptide have how many Amino Acids?
The fragments processed in the proteasome are then transported across the membrane of endoplasmic reticulum by ________________.
Transporter proteins TAP-1 and TAP-2
What is the function of HLA-DM molecule?
Removal of CLIP from the antigen binding pocke of MHC class II and assists in loading peptide into MHC class II pocket.
The invariant chain blocks the antigen binding pocket of which MHC molecule in Endoplasmic Reticulum?
MHC class II
MHC class II molecules are present on APC's and can be induced to be expressed on endothelial cells...
True or False
Which transcription factors are activated as a result of intracellular signaling within CD4t cells following stimulation?
Which subset of helper T cells switches B cell isotypes to IgE and activate eosinophils in response to allergens and parasitic worms?
Activation of a B cell by a T cell dependent antigen allows for isotype switching...true or false?
What are the 2 Pathways of Killin by Cytotoxic T cells?
-1st and most frequent is use of cytotoxic granules, released after attachment by exsocytosis
-Perforin polymerizes into transmembrane pores that increase membrane permeability
-Granzymes are serine proteases that pass into the cell and induce apoptosis (preventing lysis and releasing virus)
-2nd pathways uses interaction of CD178 (Fas Ligand) on CD8+ cell with CD95 (Fas) on host cell, using caspase proteolytic enzymes to activate apoptosis of target cells.