Immunology 3 Flashcards
What are the functions of B lymphocyes?
Produce antibodies during immune response (when become activated (plasma cells)).
Form memory B cells.
Define antibody.
Antibody = secreted protein which facilitates immune neutralisation of pathogens by binding antigens expressed on pathogen or its products.
What is the structure of an antibody?
Y-shaped protein, two heavy and two light chains.
Ends of chains are the antigen-binding region called the variable region.
Back of chains is the constant region, which provides scaffold for variable regions to sit on.
How are B cells proliferated?
DCs present antigen to B cells.
B cells travel to germinal centres in spleen cortex and undergo intense proliferation.
CD4+ T helper cells localise to paracortical areas where they produce chemicals to help B cell proliferation.
Where are B cells activated?
Activated in the white pulp of the spleen.
What happens during B cell activation?
B cell receptor is an IgM monomer on its surface.
Dendritic cell presents antigen to B cell, ligates IgM binding site and triggers B cell activation.
After activation, B cells divide at germinal centre and then become antibody-producing cells / memory cells.
Plasma cells start to secrete IgM. Later, isotype switching occurs.
Define isotype switching.
Isotype switching = the rearrangement of genes which code for antibody proteins, to achieve production of a different class of antibody.
