Antibodies, antibody diversity, and T cell development Flashcards
What is an antigen?
An antigen is anything that can be specifically bound by the cells of the adaptive immune system (B and T cell receptors)
Where are B and T cells generated? What is the process of B and T cell generation called?
They are generated in the bone marrow. Called hematopoiesis
What are the primary functions of antibodies? (4)
Antigen recognition
- bind to foreign antigen determinants
- intact antigen doesn’t need to be processed or presented
- binding alone may be sufficient to neutralize antigens
Direct antigen neutralization before a cell gets infected
Opsonization- tag a particle for destruction- enhances phagocytosis
Activation of the complement cascade to punch holes in things
What makes up an antibody?
There are two fragments: Fab- antigen binding fragment and Fc- crystallizable fragment
They have a four chain structure- 2 identical heavy chains that span Fab and Fc and 2 identical light chains that are on Fab only
What are the classes of Ig (immunoglobulin) and how do their heavy chains, morphologies, and basic characteristics differ?
IgG (immunoglobulin G) heavy chain gama IgM- heavy chain u IgA- heavy chain alpha IgD- heavy chain delta IgE- heavy chain epsilon
What is a hypervariable region?
This is the portion that allows for discrimination between microorganisms
To what does and FcR bind? What is the end result of that binding?
An FcR binds to
How is antibody diversity achieved?
It is achieved via the joining of various gene segments of V D and J genes. Genes can be rearranged and that is how so many antibodies can be made
Where do T cells mature?
Where do B cells mature?
In the thymus
In the bone marrow
What is positive and negative selection of T cells? Where does it occur?
Occurring in the thymus for T cells, the cell receptors are monitored to see how they interact with self antigens. If they bind self antigens aggressively or cannot recognize MHC, they are killed off. If they can recognize MHC, but don’t bind aggressively, they are able to graduate and are sent out into the immune system.
What is positive and negative selection of B cells? Where does it occur?
Occurring in the bone marrow, the cell receptors are monitored to see how they interact with self antigens. If they bind self antigens aggressively they are edited. If they continue to bind aggressively they are killed off. If they recognize MHC, but doesn’t bind aggressively, they are able to graduate.
Tell me about the chains, morphologies, and basic characteristics of IgG?
IgG- has 4 forms, provides the majority of antibody-based immunity against invading pathogens. The only antibody capable of crossing the placenta to give passive immunity to the fetus
Tell me about the chains, morphologies, and basic characteristics of IgM?
Expressed on the surface of B cells and in a secreted form with very high acidity. Eliminates pathogens in the early stages of B cell mediated (humoral) immunity before there is sufficient IgG
Tell me about the chains, morphologies, and basic characteristics of IgA?
Found in mucosal areas, such as the gut, respiratory tract and urogenital tract and prevents colonization by pathogens. Also found in saliva, tears, and breast milk
Tell me about the chains, morphologies, and basic characteristics of IgD?
Functions mainly as an antigen receptor on B cells that have not been exposed to antigens. It has been shown to activate basophils and mast cells to produce antimicrobial factors
