Chapter 10 Flashcards
Cell-mediated immunity is the adaptive immune
response stimulated by what?
microbes inside host cells.
It is mediated by T lymphocytes and can be transferred from immunized to naive individuals by T
cells and not by antibodies.
Differentiated effector T cells are recruited preferentially to where?
peripheral tissue sites of infection and
tissue injury, and cells that recognize antigen in
the tissues are retained. These events are mediated
mainly by adhesion molecules and chemokines
CD4+
TH1 cells recognize antigens of microbes that
have been ingested by phagocytes and activate the
phagocytes to kill the microbes. The activation of
macrophages by TH1 cells is mediated by what?
IFN-γ and
CD40L-CD40 interactions. Activated macrophages
kill phagocytosed microbes ingested into phagolysosomes by the actions of reactive oxygen and
nitrogen species and enzymes (called classical
macrophage activation). Activated macrophages
also stimulate inflammation and can damage
tissues
CD4+
TH2 cells recognize antigens produced by what?
helminths and other microbes as well as environmental antigens associated with allergies
IL-4,
secreted by activated TH2 cells, promotes what?
B cell
isotype switching and production of IgE, which
may coat helminths and mediate mast cell deregulation and inflammation
IL-5 secreted by activated TH2 cells activates what?
eosinophils to release
granule contents that destroy helminths but may
also damage host tissues
. IL-4 and IL-13 together
provide what?
protection at epithelial barriers (barrier
immunity) and induce an alternative form of macrophage activation that generates macrophages
that mediate tissue repair and fibrosis.
CD4+
TH17 cells stimulate neutrophil-rich inflammatory responses that eradicate what?
e extracellular bacteria and fungi. TH17 cells may also be important
in mediating tissue damage in autoimmune
diseases.
CD8+
CTLs kill cells that express what?
peptides derived
from cytosolic antigens (e.g., viral antigens) that
are presented in association with class I MHC molecules
CTL-mediated killing is mediated mainly
by granule exocytosis, which releases what?
granzymes
and perforin. Perforin facilitates granzyme entry
into the cytoplasm of target cells, and granzymes
initiate several pathways of apoptosis
. CD8+
T cells
also secrete IFN-γ and thus may participate in
defense against what?
phagocytosed microbes and in
DTH reactions
γδ T cells and NKT cells are small populations of
lymphocytes that express what?
antigen receptors of
limited diversity and recognize a wide variety
of antigens, including peptides and small
molecules (γδ cells) and lipids (NKT cells).
Some
of these cells are located in epithelia and are
believed to respond against what?
conserved microbial
antigens. The functions of these cells are not well
defined.
