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linked suppression 456 Listeria immunity
Cells
produce 1250
clones cells
in culture
2750
cells
Lymphocytes from
potential donor
6250
cells
8750
cells
linked suppression
Mechanism whereby peripheral tolerance to one antigen
extends to other antigens nearby within the same host.
Dependent on regulatory T cells.
linker of activation in T cells (LAT)
An adaptor cytoplasmic protein with several tyrosines that
are phosphorylated by ZAP-70, a tyrosine kinase. It associates
with membrane lipid rafts and coordinates downstream
signaling events in T lymphocyte activation.
lipid raft
A plasma membrane subdomain rich in cholesterol and
glycosphingolipid in which cellular activation molecules are
concentrated. Proteins in an activated T cell requisite for T
cell receptor signaling interact with the rafts and produce a
large stable immunosome that attracts and activates more
molecular signals. The rafts and signaling molecules act
with the T cell receptors’ cytoplasmic regions to transduce
T cell receptor signaling to the nucleus.
lipopolysaccharide (LPS)
Refer to endotoxin. Refer to LPS.
liposome
A spherical lipid vesicle comprised of 5-nm phospholipid
bilayers that enclose one or several aqueous units. These
microspheres can be produced by dispersing phospholipid
mixtures with or without sterols in aqueous solution. The
liposomes produced consist of concentric phospholipid
bilayers and thus represent ideal models of cell membranes
into which antigens may be embedded to induce an immune
response. They also have been used to deliver drugs. They
may or may not fuse with cell membranes, and other problems
surround their use, e.g., whether they will leave the
circulatory system or be phagocytized by reticuloendothelial
cells. Liposomes may act as immunologic adjuvants
when antigens are incorporated into them. Liposomes
serving as biological membrane models have also been used
in studies on complement-mediated lysis. They may serve
as vehicles for vaccine delivery if the vaccine antigen is
incorporated in the aqueous solution.
lipoxygenase pathway
Enzymatic metabolism of arachidonic acid derived from the
cell membrane which is the source of leukotrienes.
liquefactive degeneration
Dermal–epidermal interface liquefaction induced by
immune mechanisms. This process engages basal cells,
Fraction of Microcultures That did not Respond
1
0.1
0.01
0
Limiting dilution.
0
2500
5000
Cells/Well
7500
10000
leading to coalescing subepidermal vesicles in such skin
diseases as dermatitis herpetiformis, erythema multiforme,
fixed drug reaction, lichen planus, lupus erythematosus, and
many other conditions.
lissamine rhodamine (RB200)
A fluorochrome that produces orange fluorescence.
Interaction with phosphorus pentachloride yields a reactive
sulfonyl chloride useful for labeling protein molecules to be
used in immunofluorescence staining.
Macrophage
Listeria.
Macrophage
Listeria
A genus of small Gram-positive motile bacilli that have
palisade growth patterns. The best known is L. monocytogenes,
which has a special affinity for monocytes and
macrophages, in which it takes up residence. It may be transmitted
in contaminated milk and cheese. Approximately
one third of the cases occur in pregnant females, resulting
in transplacental infection that may induce abortion or
stillbirth. Infected infants may develop septicemia, vomiting,
diarrhea, cardiorespiratory distress, and meningoencephalitis.
Individuals with defective immune reactivity
may develop endocarditis, meningoencephalitis, peritonitis,
or other infectious processes. Treatment is with ampicillin,
erythromycin, gentamycin, or chloramphenicol.
Listeria immunity
Immune responsiveness to Listeria has been investigated
mostly in mouse models. The microorganism may be found