Antibodies, Antibody Diversity and T-cell development - Powell Flashcards
What is an antigen?
Anything that can be specifically bound by cells of the adaptive immune system (B or T cells).
Which cells bind in a specific manner to antigen (Ag)?
The lymphocytes
- T cells (cell meditation immunity)
- B cells (Humoral immunity)
What is an antibody?
Also known as an immunoglobin it is a membrane bound B cell receptor.
What are the primary functions of antibodies?
- antigen binding and recognition
- Bind ALONE may neutralize antigen. - Trigger the elimination of foreign Antigen.
- Direct antigen neutralization
- opsonization
- activation of the complement cascade
Where are B cells and T Cells generated?
Both begin in the bone marrow
What is a hyper-variable region?
Where antigens bind.
Where do T cells mature?
the Thymus
- Postive selection = cortical region
- negative selection = Medullary region
Where do T cells mature?
In the cortical region of the Thymus
Where do T cells mature?
In the Thymus
To what does FcR Bind?
Binds to Fc region on antibody
What is the end result of FcR Binding?
Keeps pathogen close, allowing effector cell to preform opsonization on pathogen.
Describe positive and negative selection of T cells and where it occurs…
Cells are either kept or deleted based on how they interact with antigens (IE they are removed if they don’t play nice with self antigen.)
Positive selection = kept b/c of low avidity interaction with self antigens.
Negative selection = deletion if cell responds with high avidity with self antigens.
How is antibody diversity achieved?
Because of the human heavy chain variable region. This is possible due to VDJ gene segments. (variable, Diversity & joining)
What is hematopoiesis?
Production of RBC
Where do B cells mature?
In the bone marrow
What are the components of Antibodies?
Two fragments
- Fab = antigen binding (light chains only found here)
- Fc = crystallizable fragment
4 Chain structure
- 2 identical heavy chains that spans Fab and Fc
- 2 identical light chains = only Fab
Classes of immuoglobins are defined by what?
Heavy chain differences.
Where are IgA’s found?
Mucosal areas, saliva and breast milk
Where are IgD’s found?
Functions mainly as antigen receptor on B cells that have not been exposed to antigens.
What do IgE’s do?
Binds to allergens and trigger histamine release from mast cells and basophils.
What does IgG do?
4 forms: provides majority of antibody based immunity adjacent invading pathogens. *Only antibody capable of passing over placenta to give passive immunity to fetus.
What is Combinatorial diversity?
Is the creation of antibody diversity in the Ig repertoire through the joining of various gene segments.
What is a naive B Cell?
One that has never seen its antigen before
The ability of a cell to undergo class switching allows what?
Allows for the generation of multiple antibody isotopes with the same antigen specificity.
Where does IgM reside?
On naive B cells
Do T cells undergo class switching?
No! only B cells (Plasma cells)
Do T cells undergo class switching?
No! only B cells!
The Lymphocytes that do not bind do MHC through their TCR are destine for what?
destine to die via apoptosis
The BCR on Naive B cell can only be ____ OR ______.
IgM or IgD
