Antibody Classes Flashcards
What are the five classes of antibodies?
IgM IgG IgA IgD and IgE
What are the basic components of all antibodies?
Variable region that binds antigen and constant region that determines class and function
What is the main function of IgM?
Primary immune response efficient at complement activation and acts as an opsonin
What is the structure of IgM?
Pentamer with 10 antigen-binding sites includes a J chain
What is the role of IgG?
Secondary immune response neutralization opsonization and placental transfer
How many subclasses of IgG exist?
Four IgG1 IgG2 IgG3 and IgG4
What is the function of IgA?
Neutralization of pathogens at mucosal surfaces present in secretions like saliva and breast milk
What is the structure of secretory IgA?
Dimer with a J chain and a secretory component for protection against cleavage
What is the role of IgD?
Acts as an antigen receptor on immature B cells and aids in their activation
Why is IgD found at very low levels in serum?
It is mostly found on the surface of B cells rather than in circulation
What is the primary function of IgE?
Mediates allergic responses and defense against parasites by binding to mast cells and basophils
What happens when IgE binds an antigen?
Triggers degranulation of mast cells and release of histamine and other inflammatory chemicals
Which antibodies are involved in complement activation?
IgM is the most efficient IgG3 and IgG1 are also involved
Which antibody can cross the placenta?
IgG specifically subclasses IgG1 IgG3 and IgG4
Where is IgA primarily found?
In mucosal tissues and secretions like saliva tears and intestinal fluids
What is opsonization?
Coating a pathogen with antibodies like IgG or complement C3b to enhance phagocytosis
How do antibodies neutralize pathogens?
By blocking their ability to bind to host cells or neutralizing toxins
Which antibody is predominant in the primary immune response?
IgM
Which antibody is predominant in the secondary immune response?
IgG
What is antibody-dependent cellular cytotoxicity ADCC?
A process where antibodies like IgG1 and IgG3 recruit natural killer cells to destroy target cells
How do antibodies enhance phagocytosis?
Fc regions of antibodies bind Fc receptors on phagocytes improving pathogen uptake
What is the half-life of IgM and IgG?
IgM has a half-life of about 10 days while IgG has a half-life of about 21 days
What is the importance of IgE in allergies?
Binds to allergens and triggers histamine release causing allergic symptoms
What is the role of the secretory component in IgA?
Protects IgA from enzymatic degradation in mucosal environments
What is the main effector function of antibodies?
Binding to antigens and recruiting other immune system components for pathogen destruction
