Humoral Immunity Flashcards
What do B cells need to become active
Antigen binding
helping signals
What happens after a B cell becomes fully activated
Clonal expansion
differentiation into plasma cells
What is the function of plasma cells
make and secret antibodies which circulate and bind to antigens on pathogenic cells
Which type of antibodies is first secreted by short-lived plasma cells
IgM
low affinity
Which antibodies are high affinity
IgG
How do B plasma cells switch from producing low affinity to high affinity antibodies
variable region mutates for better fit
what do B cells differentiate into after producing high affinity antibodies
Long lived Plasma cells
Long lived memory B cells
How do B cells become fully activated
opsonised antigen internalised by B
Protein antigen broken down
Peptide expressed as MHC 2 on B cell
TFH expresses receptor which binds to peptide
What are the 2 functions of antibodies
recognition function
effector function
How does the recognition antibody function aid the immune system
bind to antigen
stops function of antigen
viruses can no longer infect cells
What form of IgM serves as the B cell antigen receptor
membrane bound monomeric
what form of IgM is secreted during the humeral immune response
secreted
pentameric
Why is IgM secreted in pentameric form
contains 10 antigen binding sites
What is agglutination
build up of cross linked antibodies and antigens producing a clump
How does agglutination aid in pathogen elimination
holds pathogens in place for engulfing
prevents viruses from binding/infecting host cells
What type of antibody is most abundant in normal human serum
IgG
what are the functions of IgG
agglutination
complement system activation
foetal immune protection
opsonisation
natural killer cell activation
How are foetus’ protected from pathogen without a developed immune system
antibodies transported across the placenta directly into foetal blood circulation
Why is a baby’s immune system most vulnerable at 6 months
maternal IgG antibodies degrade
baby not fully producing own yet
Which antibodies contain the mechanism for neutralisation
IgG
Secretary IgA
Why are IgG antibodies effective opsonins
Phagocytes express an FC receptor that binds to the constant region of the IgG heavy chain
What is the function of membrane bound monomeric IgD
B cell antigen receptor
Mediates B cell activation
How is the GI Tract of neonates protected
sIgA antibodies are transported via breastmilk
what is the mast cell activated by
IgE heavy chain
causes degranulation
