Ch.17 Adaptive Immunity Flashcards
what are antigens (Ag)?
are molecules that in the body activate lymphocytes
what do B cells do?
interact w/antigen via surface immunoglobins i.e, antibodies
what do T cells do?
interact w/ antigen via surface antigen receptors
how does interaction with antigens with smaller segments occur
epitopes or antigenic determinants
what are epitopes that elicit an immune response?
protein, peptide, or complex polysaccharides
what are variable regions?
possess variable amino acid sequences and are antigen-binding sites
what are the antibody classes of IgG, IgD, and IgE?
monomer forms
what are the antibody classes of IgM, and IgA?
are aggerates of 2 or more monomers
describe IgA
dimer
found mainly on mucosal surfaces & in secretions
prevents pathogen attachment to surfaces
describe IgG
monomer
most abundant in blood and tissue fluids
opsonization
activate complement
neutralize viruses
describe IgD
found on B cells & in blood, lymph
describe IgM
The circulating type is a pentamer
generally remains in blood vessels
first Ab detected in immune response
effective in aggulation & complement activation
describe IgE
found on the surface of mast cells & basophils
cause release of histamines & other chemicals by the cells in the presence of antigen
can attract complement, phagocytic cells
what is the humoral immune response most effective?
extracellular pathogens
what is the humoral immune response to a microbe?
is a composite of responses to different epitopes by thousands of b cells
what do B cells possess?
surface immunoglobins that bind to their specific epitope which activate B Cell
what do b cells require
T dependent antigens
T helper cells that interact with each other
how do T helper cells bind antigens?
via MHC class II receptors on B cells
what is the key to B cell response?
clonal selection
what is clonal selection?
the proliferation of B cells that respond to a specific antigen
what happens when a B cell contracts its cognate antigen?
it is stimulated to proliferate and differentiate into plasma cells (secrete antibodies) and memory cells
what are T-indpendnet antigens?
B cells do not require Th cells for activation
primary antibody response
following infection or vaccination
antibodies appear in serum after several days
during the lag period, b cells that bind antigens differentiate into:
antibody-producing plasma cells (first IgM->IgG)
secondary antibody response
via a second exposure to a pathogen or booster dose
due to memory b cells
a much bigger response with mostly IgG
basis for immunization
what are the protective mechanisms of binding antibodies to antigens?
Agglutination- reduced # of infectious units to be dealt with
opsonization-coating antigen with antibody enchancespahgocytosis
neutralization-blocks adhesion of bacteria and viruses to the mucosa
activation of complement-causes inflammation and cell lysis
antibodies attached to target cells destroy by macrophages, eosinophils, and NK cells
what is cell-mediated immunity?
it involves T cells
what do t cells do in cell-mediated immunity?
recognize antigens that are presented to them on the surface of cells infected with intracellular pathogens
what are T cytotoxic cells?
differentiate into cytotoxic lymphocytes
target self-cells altered by infection with pathogen( viruse & bacteria);cancer cells
what do T cytotoxic cells do?
recognize endogenous antigens combined with MHC class I molecules via CTL CD8+ co-receptor
What do T cytotoxic cells kill?
kill target cells via perforin orations and induction of apoptosis by the introduction of granzymes into the target cell
what do T helper cells recognize?
antigens presented by antigen-presenting cells (APCs)
specifically dendritic cells and macrophages
How do CD4+ co-receptors help T helper cells?
allows T helpers to bind antigens combined with MHC class II molecules on the APCs
what does the activation of T helper cells cause?
release of various cytokines
t helper 1 cells:
cytokines activate macrophages, complement, promote inflammation & opsonization, & differentiation of CTLs
T helper 2 cells:
cytokines mainly for antibody production by B cells
naturally acquired
ACTIVE
active: antigens enter the body naturally body induces antibodies
naturally acquired
PASSIVE
passive: antibodies pass from mother to fetus via placenta or to infant
Artificially acquired
ACTIVE
antigens are introduced in vaccines;
body produced antibodies
Artificially acquired
PASSIVE
preformed antibodies in immune serum are introduced by infection
which antibody is the response is fastest, largest, and longer, and what causes it?
secondary antibody response
due to memory B cell
