B and T Cell Immunity Flashcards
B cells attack invaders __side the cell
Outside
T cells attack invaders __side the cell
Inside
What is the combination of T Lymphocyte, MHC Class and CD for T helper and T cytotoxic cell?
T Cytotoxic Cells, via MHC Class I, CD8+
T Helper Cells, va MHC Class II, CD4+
Describe the structure of MHC Class I
Tetramer, of alpha 1, 2, 3 and beta 2 microglobulin subunits
MHC Class I is expressed on what cells?
All nucleated cells (Not RCBs)
99% of MHC Class I molecules carry self-proteins to help determine self from non self. But some self-proteins are very big - how do they fit into the blinding cleft of MHC Class I?
- Formation of proteins occur via ribosomes
- Any defective ribosomal products and old proteins are sent to the proteasome for degradation to generate peptide products 8-9 AAs long
- The MHC Class I molecule is then synthesised in the ER
- TAP transports 8 AA long peptides into the ER
These small proteins are then translocated to the MHC Class I binding cleft
Give examples of two viruses which have avoided detection by MHC Class I through inhibition of TAP?
Human Simplex Virus 1
Human Cytomegalovirus
Describe the structure of MHC Class II
Tetramer, of beta 1, beta 2, alpha 1, alpha 2
Which MHC Class binds to longer peptides?
MHC Class II
On which cell types is MHC Class II expressed?
B cells
Dendritic cells
Marophages
How are proteins inserted into the MHC Class II binding cleft?
The antigen is taken up into intra-cellular vesicles. Proteases breakdown antigens into fragments, and fuse with MHC Class II
Why don’t MHC Class II molecules not load with peptide in the ER as it does with MHC Class I?
Invariant chain binds and prevents peptide loading into the ER
Where are T Lymphocytes developed?
Early development in Bone marrow, later development in Thymus
What is the source of antigenic material for MHC Class I?
Cytosol / internal
What is the source of antigenic material for MHC Class II?
Endocytic Vesicles / External
