Exam 1: Antigen processing Flashcards
Present antigen to naive CD4 and CD8 t cells so they initiate t cell responses
Dendritic cells
Present antigens to differentiated CD4 t cells in the effector phase of cell mediated immunity
Macrophages
Present antigens to helper t cells (CD4) during humora immune resp.
B lymphocytes
What are the two important functions of APCs?
- Convert P antigens to peptides and display peptide-MHC complexes
- Co-stimulation to T cells
Processing of endocytosed antigens for MHC class II sequence of events:
- Uptake into vesicular compartments
- Processing in endosomal and lysosomal vesicles
- biosynthesis and transport of MHC class 2 molecules
- Asssociation with MHC class 2 molecules
- Expression on the APC surface
What are the 3 APCs?
- DC
- Macrophage
- B cells
What 3 things induce MHC II on macrophages?
- PAMPS
- DAMPS
- Cytokines
What are the 3 functions of APCs?
- Capture
- Digest
- Display
Antigen presentation begins with _____.
Antigen processing
What do the pathways of Antigen processing do?
convert protein antigens into peptides and load them on MHC molecules to be displayed to lymphocytes
antigens present in the acidic vesicular compartments of APCs generate _____ associated peptides.
MHC class II
antigens present in the cytosol generate _____ associated peptides
MHC class I
Acidic compartments that contain proteolytic enzymes
Endosomes
What fuses with endosomes to form phagosomes?
Lysosomes
The most important proteolytic enzymes involved in protein degredation
Cathepsins
Association of processed peptides with class 2 MHC molecules takes place in:
a. Endosomal compartments
b. Endoplasmic reticulum
c. Golgi apparatus
d. Proteosome
a. Endosomal Compartments
Which of the following statements is NOT true?
a. Exogenous acquired proteins will generate peptides that activate CD4T cells
b. Endogenously acquired proteins will generate peptides that activate CD8T cells
c. Cytotoxic cells are stimulated by B cells that present antigen through MHC
B.
What are the steps for processing Cytosolic antigens for MHC class I:
- Cytosol location
- Proteolytic degradation in proteosome
- Transport to ER
- Assembly in ER
- Surface expression
T/F. Sometimes even endocytosed antigens may be presented through MHC class I molecules
T
Proteins synthesized in the cytosol are ubiquitinated thus destined for ______
Proteosomal degradation
What is the main transporting system to get peptides to the ER?
Transporter associated with antigen presentation TAP
Where is TAP located?
Memb. of ER
______ acquired proteins will generate peptides that activate CD4 T cells
Exogenously
______ acquired proteins will generate peptides that activate CD8T cells
Endogenously
Surface molecule found on T cells that recognizes antigen presented in the correct MHC complex
TCR
What are the 2 types of TCR?
- aB TCR
2. yd TCR
Which TCR is the most common?
aB TCR
Which TCR is found on the T cells in lymphoid tissue
aB TCR
Which TCR is found on T cells at mucosal surfaces?
yD TCR
T/F. Each T cell contains TCRs of multiple specificities?
F. only one specificity
T/F aB TCR is MHC Dependent
T
T/F. yD TCR is MHC Dependent?
F. independent
Group of proteins closely associated with TCR
CD3 Complex
What function does the CD3 Complex have?
transduces activation signals to nucleus following antigen interaction with TCR
When T cells from one individual recognize foreign peptides only when bound to and displayed by MHC molecules of that individual
Self MHC restriction
CD4 T cells are MHC class ___ restricted
2
CD8T cells are MHC class ___ restricted
1
CD4 MHC class 2 restricted T cells recognize peptide antigens derived from ______ .
Extracellular/Exogenous P that are internalized into vesicles of APCs
CD8 MHC class 1 restricted T cells recognize peptides derived from______.
Cytosolic/Endogenously synthesized proteins
T/F. The BCR interacts with the MHC molecule
F.
T/F. B cells can recognize soluble antigens as well as antigens exposed on cell surfaces
T
Lipid antigens are presented by molecules called ____.
CD1
Where are CD1 molecules found?
APCs and epithelial cells
Who Do CD1 molecules present antigens to?
T cells that are not MHC restricted
NKT-cells
What is the first signal in co stimulatory signaling
Specific signal
Generated by interaction of an antigenic peptide bound in the MHC cleft with the TCR-CD3 complex
What is the second signal in co stimulatory signaling?
Co-stimulatory signal
Provided by interaction b/t CD28 on T cells and members of B7 family on the APCs
What happens when T lymphocytes are stimulated without a co-stimulatory signal?
clonal anergy
A state of no responsiveness, which occurs when a co-stimulatory signal is absent
Clonal anergy
presentation of antigens through class 1 pathway
cross-presentation
