ch 4 Flashcards
where do b cells originate and begin development?
bone marrow
what organs and folicles do the b-cells go through in order. (more details in ch. 6)
Bone marrow(begin development)->secondary lymphoid organ (go through circulation) -> secondary lymphoid follicle (b-cells complete maturation and differentiation- turn into the plasma cell)
what is the difference between a immunoglobulin (b-cell receptor) and a antibody
a b-cell receptor is membrane bound and contains a trans-membrane region. there is a heavy chain in a y shape and attached to the sides are light chains. Antibodies are the secreted form of immunoglobulin and are secreted by plasma cells. therefore, they are not membrane bound. While they also have heavy chains and light chains, they are broken up into the constant and variable regions. the tip of the y shaped anitbody is the variable region (FAB) and the rest is the constant region (FC). the constant region has the effector function and is what the other cells use to identify the antibody.
how many Ag specificities does a b-cell have?
one
how is the antibody isotype determined
heavy chain name. Each isotype has its own heavy chain.
the light chains can only be what 2 things
Kappa or Lambda
what are the parts of the antibody
the variable region, constant region, hinge region and the antigen binding sites at the variable region
what does the FAB region consist of
Heavy and light chain constant region and heavy/light chain variable region and antigen binding sites
what isotype has the flexible hinge and what is the advantage?
IgG has flexible hinges that twist to bind to different antigens and helps them to reach more than one on the same organism. Meaning they can bind both their arms to an antigen.
what are the 2 isotypes that lack hinge regions
IgM and IgE. they are rigid and have longer constant regions.
what are the different antibody isotypes and what are they for/ where are they found?
IgM- the prototype (rough draft) secreted or on the cell
IgD- b-cell receptor on the cell (no secreted form always bound to the b-cell)
IgG- most common in plasma. can cross the placenta to the fetus
IgA- found in gut and secretions (mucus, milk, saliva and tears)
IgE- associated with allergies, parasites and anaphylaxis
what is the structure of the different isotypes
IgG- monomer (2 binding sites)
IgM- pentamer (10 binding sites)
IgD- monomer
IgE- monomer
IgA- dimer (4 binding sites)
what is the structural basis of antibody diversity and where are they located
the hypervariable loops located at the FAB region.
what is an epitope
the thing ( a carb or protein) on the antigen the antibodies bind to
multivalent
antigen has multiple epitopes
- same repeated
-multiple different
what helps make the variable shaped on the FAB region that the epitopes bind to
HV loops
how do you make a mouse monoclonal antibody
juice up the mouse with what you want to target. eg spike protein.
then a bunch of antibodies are made and you pick the best one by testing the binding.
you fuse them with an immortalized b cell with the mouse cell and use PEG to make an immortalized cell that keeps pumping out the best antibodies.
treat with drugs where only the hybridomas survive that pumps out the selected antibodies.
then proliferate.
what does MAB stand for
Monoclonal antibodies
What are the two types of diversity in the FAB region?
germline- inherited
somatic
what are the 2 types of somatic diveristy
recombination and junctional diveristy
recombination diversity is where the inherited genes are rearranged and junctiontional diversity happens when the genes are glued together (the coding joints)
germline diversity
Igs are all chopped up and only b cells can express them. They are arranged sequentially on the chromosomes. so the germline are inherited then the rest of the diversity is from gene rearrangement. immature b cells are the only ones that do this.