Quiz 2- Antigens/Antibodies Flashcards
Where are class I MHC found?
All nucleated cells in the body
Where are class II MHC found?
Professional antigen presenting cells such as dendritic cells, macrophages, B lymphocytes, and thymocytes
Which class of MHC is an inhibitory receptor for NK cells?
Class I
Where does peptide bonding occur in class I MHC?
Between α1 and α2 domains (greatest area of variability). Closed ends (8-10AAs fit)
What is the structure of MHC class I?
Heterodimer with alpha chain 1, 2, 3 and beta chain 2 NON-covalently bound for support
What is the structure of MHC class II?
Alpha chain 1 & 2 plus beta chain 1 & 2 held together by peptide
Where does peptide bonding occur in class II MHC?
Between α1 and β1 domains (greatest area of variability). Open ends (13-18 AAs fit)
Why are there pockets in the floors of the peptide–binding clefts?
For the side chains of amino acids to fit into and anchor the peptides in the cleft
Which types of antigen presenting cells express class I versus class II MHC?
Dendritic cells and B lymphocytes express class II, macrophages express class I
Antigens entering via the periphery are filtered by what?
Lymph and lymphoid tissues
Antigens entering via the blood are filtered by what?
The spleen
What are the only type of cells that can activate naïve T cells?
Dendritic cells
What types of antigens are presented with class I MHC?
Intracellular pathogens and self
What types of antigens are presented with MHC class II?
Extracellular pathogens
How are class II HLAs made?
The alpha and beta chains are synthesized in the ER where they are held together by the invariant chain which blocks peptide binding in the groove. Once the molecule leaves the Golgi, the invariant chain is broken down by lysosomal enzymes and leaves behind CLIP. CLIP is replaced with the antigen by HLA-DM in a late endosome before transport to cell membrane.
