Lecture 12 Flashcards
What is an epitope?
A short amino acid sequence that is recognized by antibodies and T cells
How many amino acids tend to be in epitopes?
8-20 amino acids
What are the differences between primary and secondary immune responses?
- Primary: 1st exposure to an antigen, 7-10 days antibody detected and peaks at 15 days, falls off quickly
- Secondary (memory): second exposure, hrs-days antiboidy detected and peaks at 2-3 days much higher peak and falls of slowly
What are the three kind of lymphocytes?
- CD4 T cells
- CD8 T (CTL) cells
- B cells
Which cells use Class I MHC?
CD8 T cells
Which cells use Class II MHC?
- CD4 T cells
- B cells
How does the Class II MHC on Professional APCs (antigen presenting cells)?
The professional APCs express class II MHC on macrophages, dendritic cells, and B cells. When a pathogen is inside a phagosome, its epitopes enter the pathway
How does the Class I MHC pathway work?
A Class I MHC molecule on an infected cell attaches to a T cell receptor upon finding a CD8 T Cell.
What happens during the lag-period of primary exposure?
This is when clonal selection happens with naive lymphocytes, which makes many, identical plasma cells (effectors) that make antibodies.
What does it mean for a lymphocyte to be naive?
The lymphocyte has not yet differentiated
What does it mean for a lymphocyte to be an effector?
The lymphocyte starts looking for its epitope
What does it mean for an epitope to be a memory cell?
It stays on the lookout for its epitope but is not immediately activated
What is a plasma cell?
Plasma cells are the cells that make antibodies (effectors)
What part of the antibody determines its class?
The constant region (made of only the heavy chain)
What part of the antibody determines its binding site?
The variable regions (made of the light and heavy chains)
