Antigen Processing, Presentation, Co-Stimulation Flashcards
Can a T cell recognize an entire microbe?
NO.
What is the only thing that will activate a T cell?
Cell surface PEPTIDES presented by cells that express MHC
What is the primary Antigen-presenting cell?
Dendritic cells
Where are dendritic cells found?
Mostly in skin, mucosa, lymph nodes, spleen, thymus
Which MHC molecule do dendritic cells express?
MHC II
Dendritic cells are the link between the ___________ and __________.
Innate and adaptive immune systems
T/F: Macrophages are phagocytic cells.
TRUE
T/F: Dendritic cells are important for both clearing debris (phagocytosis) and antigen presentation.
FALSE.
Macrophages!
What are the three antigen presenting cells?
- Dendritic cells
- Macrophages
- B cells
What makes a cell a professional antigen presenting cell (APC)?
A cell that naturally expresses MHC II
What interacts with the microbe at the site of infection?
Antigen Presenting Cell
Where do APC and naive T and B cells interact?
Lymph nodes
Which MHC is found on all nucleated cells?
MHC I
Which cells have MHC II?
APCs
What types of proteins are bound to MHC I?
Cytoplasmic proteins
What types of proteins are found on MHCII?
Extracellular proteins
T/F: CD8+ T cells recognize MHC II?
FALSE.
CD4+ recognizes MHC II
(II + II = 4)
Give a brief description of the structure of MHC I?
Has two alpha subunits that create a cleft between them. This cleft is where the peptides bind
Give a brief description of the structure of MHC II?
Alpha 1 and Beta 1 subunits create the peptide binding cleft.
What are the two antigen processing pathways?
- Extracellular proteins engulfed by professional APCs are processed and displayed by MHC II molecules
- Cytoplasm proteins processed and displayed by MHC I molecules
Understand the pathways for antigen processing!!
Look at the slides
T/F: Once a T cell recognizes MHC, it will immediately activate.
FALSE.
Multiple receptors on T cells need to be engaged to activate the cell
Which receptor recognizes the antigen in a T cell?
TCR
Which proteins begin the signaling after TCR recognizes antigen?
CD3 (associated with TCR)
In a T cell, _____ recognizes antigens, while _____ recognizes the corresponding MHC
TCR; CD4/CD8
The binding of all of _____________ receptors in the ________ ________ of a T cell will activate the cell.
co-stimulatory; immunological synapse
What are the co-stimulators molecules and their receptors?
- B7 with CD28
2. ICAM-1 with LFA-1
In order to deactivate a T cell, ____ will bind to ______.
B7; CTLA-4
What two ways does CTLA-4 terminate the function of T cells.
- Competes with CD28 for B7
2. Actively blocks signals from TCR and CD28 to the nucleus
