37 Questions
Which cell types can express HLA-2?
Macrophages and dendritic cells
Which type of antigen (intracellular or extracellular) corresponds to HLA-1 presentation?
Intracellular
What is the process by which exogenous antigens can be presented by HLA-1?
Antigens leaking out of endosomes into the cytosol
What is the function of cross-presentation in antigen presenting cells?
Simultaneously activating both Thelper and cytotoxic T cells
After a peptide-bound HLA-2 is expressed on the cell surface, what happens next?
It binds with CD4+ T-cells
What is the primary role of dendritic cells in cross-presentation?
Being the best at cross-presentation
What is the major CD that distinguishes a Helper T-cell from a cytotoxic T-cell?
CD4
What is the co-receptor for a cytotoxic T cell?
CD8
Which molecule interacts with CD28 on T-cells for co-stimulatory activation?
CD80
Which cells have the capacity to up-regulate CD80/86 after they are activated by an encounter with a pathogen?
Macrophages
Which type of HLA is involved in the endogenous antigen presentation pathway?
HLA-1
When is the antigen loaded onto the HLA protein in the exogenous antigen presentation pathway?
After being engulfed by the antigen-presenting cell
How are cytotoxic T cells activated?
By direct recognition of antigens displayed on MHC class I molecules
What types of cells might present the HLA bound antigen in the endogenous antigen presentation pathway?
All nucleated cells
What distinguishes foreign antigens from self antigens for T-cells?
The binding affinity to HLA proteins
Why can HLA proteins present a wide variety of antigens to a wide variety of lymphocytes?
They are not bound particularly tightly to antigens
How is an HLA class II molecule loaded with antigen?
Via the exogenous pathway in endocytic compartments
Under what circumstances can exogenous antigens be presented by HLA class I molecules?
During antigen crosspresentation in endocytic compartments
What ensures that a cytosolic antigen isn’t loaded onto an HLA-2 in the rough endoplasmic reticulum?
HLA-DM assisting with loading onto HLA-2
In the endogenous pathway of HLA-1 expression, where is the source of the antigenic peptide?
Cytosol
What is responsible for loading the antigenic peptide onto the HLA-1 protein in the endogenous pathway?
TAP
What happens to the loaded HLA-1 in the endogenous pathway?
It is expressed on the cell surface
What is the source of the antigenic peptide in the exogenous pathway of HLA-2 expression?
Extracellular space
Where are HLA-2 bound peptides transported to in the exogenous pathway?
Endoplasmic reticulum
What happens to the loaded HLA-2 in the exogenous pathway?
It is expressed on the cell surface
What is the main difference between antigens in endogenous and exogenous pathways?
Source of antigens: Cytosol for endogenous, extracellular space for exogenous
Where is the does the antigen bind on an HLA-1 molecule?
Between Alpha-1 and Alpha-2 Subunits
CD8 binds to the alpha-3 subunit of HLA_1
True
Where is the does the antigen bind on an HLA-2 molecule?
Between Alpha-1 and Beta 1 subunits
Which of the following cells always express high levels of HLA-2?
Dendritic cells
B-cells always express HLA-2 at low levels
True
___________ needs to be up-regulated in concurrence with HLA-2 expression (think of a process not a molecule)
Phagocytosis
Which of the following will prevent an exogenous antigen from loading onto an HLA-1?
Invariant chain
The chopped version of the invariant chain is known as _______
CLIP
Dendritic cells are the only APC that always express CD80/86
True
cSMAC includes the binding between TCR and an HLA only
False
What is the effect of paracrine signaling between APC and T-cells?
It will affect polarization of T cell
Test your understanding of T-cell activation and co-receptors with this quiz. Explore the roles of antigen presenting cells, T-cell receptors, HLA-2 molecules, and CD4 co-receptors in the immune response.
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