antigens and antibodies Flashcards
immunogenicity
property of a molecule that allows it to induce an immune response
increased when a molecule is injected along with an “adjuvant,” which prolongs molecule’s retention in the body so that a more vigorous response can be mounted
antigenicity
property of a molecule that allows it to react with an antibody
all immunogens are antigenic, but not all antigens are immunogenic
hapten
small molecules that cannot induce antibody formation but can react with antibody
must be coupled to a carrier molecule in order to induce antibody formation
an antigen, but not an immunogen
e.g., penicillin
five features required to generate immune response against an immunogen
a
mechanisms by which neoantigens are formed
proteolysis
linear vs conformational determinants
T lymphocytes can ONLY recognize linear
antibodies can recognize both
most common antigen
IgG (70% of total Ig pool)
has longer half-life than other Igs
most immunogenic antigen
IgM
titer
a
monoclonal vs polyclonal antisera
a
where is antibody found
surface of B lymphocytes
blood plasma/serum
surface of mast cells and basophils (IgE)
secretory fluids (saliva, milk)
cell types that express antibody
a
IgG
most abundant Ig
secretory form is a monomer
good activator of classical complement pathway (G3 > G1 > G2)
G4 does not activate complement
predominant antibody produced in secondary immune response
only Ig capable of crossing the placenta
present in mother’s milk
IgG1 and 3 can opsonize and coat tumor/virus cells to facilitate ADCC by NK cells and macrophages
IgM
secretory form is a pentamer
structure stabilized by J chain
excellent activator of complement (better than IgG)
predominant antibody produced in primary immune response
IgD
low conc in serum
on surfaces of antigen-naive B lymphocytes along with IgM
important in signal transduction across plasma membrane resulting in antigen-driven B-cell activation
IgE
secreted as monomer
allergies and anaphylaxis
ADCC of parasitic infections
IgA
mediator of mucosal immunity b/c can be transported across mucosal barriers
present in tears, colostrum, milk, saliva
in serum, a monomer; in secretions, a dimer
in serum, ratio of IgA1 to IgA2 is 4:1
in gut, ratio is 3:2
important in parasitic infections (helminths)
affinity
strength of binding antigen for one antigen combining site
avidity
overall strength of attachment of an antibody
takes into account how many antigen combining sites
affinity maturation
average affinity for a population of antibodies increases with repeated immunization with antigen
idiotype
a
epitope
a
specificity is due to
lymphocytes having cell membrane receptors that distinguish between epitopes
immune responses abate with time due to
removal of antigen
activated lymphocytes dying within a short period by apoptosis
regulatory immune mechanisms
