B cells and antibodies: a response to extracellular pathogens Flashcards
What is humoral response characterized by
Secretion of antibodies by B cells
Activation of B cells
When an antigen binds to a B cell, the cell takes in a few foreign molecules by receptor mediated endocytosis. Class II MHC of the B cell then presents antigen fragment to a helper T cell. An activated B cell gives rise to plasma cells
Plasma cells
Produced by an activated B cell. Secrete 2000 antibodies every second but only live 4-5 days
Most antigens recognized by B cells have multiple_______
epitopes
A variety of B cells activated by one antigen will give rise to plasma cells procucing antibodies directed against_______
different epitopes of the common antigen
What do antibodies do to pathogens
They do not kill them, they only mark them for destruction
Neutralization
Antibodies bind to viral surface proteins preventing infection of a host cell
What does the binding of antigens to toxins in body fluids do
Prevents them from entering the body cells
Opsonization
antibodies bind to antigens on bacteria
What triggers a cascade of complement protein activation
Antigen-antibody complexes bind to a complement protein
What forms a pore in the membrane of a foreign cell leading to its lysis
Membrane attack complex
Immunoglobulin
an antibody expressed by B cells
How many classes of immunoglobulin (Ig) can B cells express and what are their differences
- They have similar antigen binding specificity but different heavy chain C regions
Types of immunoglobulin
IgD, IgA, IgE, IgG, and IgM
Soluble Ig
IgA, IgE, IgG, IgM
