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lepromatous leprosy 445 leukapheresis
Irwin H. Lepow.
These cells are found in lepromatous leprosy but are not
observed in tuberculoid leprosy.
lepromatous leprosy
A chronic granulomatous disease induced by
Mycobacterium leprae. The condition is contagious and is
also known as Hansen’s disease. A second form known as
tuberculoid leprosy is a more benign and stable form. Both
forms infect the peripheral nervous system.
lepromin
A heat-inactivated extract of skin nodules laden with
Mycobacterium leprae. It is used as a skin test antigen,
which, upon intradermal injection, induces formation of
a nodular granuloma within 2 to 4 weeks in patients with
tuberculoid leprosy but not in those with lepromatous
leprosy who are anergic. The development of a positive test
signifies the presence of cell-mediated immunity against M.
leprae.
lepromin test
A tuberculin-type skin test in which a Mycobacterium
leprae suspension of microorganisms is used as the test
material. This delayed-type (type IV) hypersensitivity reaction
is negative in lepromatous leprosy but positive in tuberculoid
leprosy as well as in normal subjects. The reaction
may occur early and peak at 24 to 48 hours (described as a
Fernandez reaction), or it may occur late at approximately
4 weeks (referred to as a Mitsuda reaction). Although not
useful in diagnosis, this test has been used in the past to
classify leprosy and to give some idea of prognosis.
leptin
Endothelial cells express OB-Rβ, the leptin receptor. In
addition, leptin, the anti-obesity hormone, is an endothelial
cell mitogen and chemoattractant that induces angiogenesis
in a cornea implant model.
Leptospira immunity
Newly isolated leptospires evade the host immune system
by not reacting with specific antibody, which permits their
multiplication. On entering the host, they also evade the
host immune system by their sequestration in renal tubules,
uterine lumen, eye, or brain. The humoral immune response
is marked by production of immunoglobulin M (IgM),
which together with complement and phagocytic cells
begins to clear leptospires from the host. This is followed
by the production of opsonizing and neutralizing IgG.
Cell-mediated immunity to Leptospira infection is only low
grade. Vaccines for use in animals consist of chemically
inactivated whole Leptospira cultures, which have proven to
be somewhat effective. The immunity induced is serovarspecific.
These antibodies do not afford protection. Virulent
leptospires are better immunogens than are avirulent
organisms. It is significant that antigens located on the outer
envelope maintain their natural configuration. Both IgM
and IgG are induced following parenteral administration of
a vaccine, as the IgM is a more efficient agglutinating and
neutralizing antibody for leptospires than is IgG.
Lesch–Nyhan syndrome
A deficiency of hypoxanthine-guanine phosphoribosyl
transferase that leads to neurological dysfunction and
B cell immunodeficiency.
LESTR
Leukocyte-derived 7-transmembrane domain receptor.
LESTR is a member of the G protein-coupled receptor family,
the chemokine receptor branch of the rhodopsin family.
Tissue sources include the human blood monocyte cDNA
library and human fetal spleen. It is expressed on monocytes,
neutrophils, lymphocytes, and phytohemagglutinin (PHA)activated
T cell blasts. CHO and COS cells transfected with
LESTR fail to bind IL8, NAP-2, GRO-α, MCP-1, MCP-3,
MIP-1α, and RANTES. Also called fusin and CXCR4.
lethal dose
An amount of a toxin, virus, or other material that produces
death in all members of the species receiving it within a
specified period of time following administration.
lethal hit
The induction of irreversible injury to a target cell following
binding with a cytotoxic T lymphocyte. Exocytosis,
cytotoxic lymphocyte granules, polymerization of perforin
in target cell membranes, and the passage of calcium ions
and granzymes (apoptosis-inducing enzymes) into the cytoplasm
of the target cell are observed.
Letterer–Siwe disease
A macrophage lineage tumor (histiocytosis X) that may
appear in the skin, lymph nodes, and spleen.
Leu-CAM
Leukocyte cell adhesion molecules.
Leu-M1
A granulocyte-associated antigen. Immunoperoxidase
staining detects this marker on myeloid cells but not on B
or T cells, monocytes, erythrocytes, or platelets. It can be
detected in Hodgkin cells and Reed–Sternberg cells.
leukapheresis
A method that removes circulating leukocytes from the
blood of healthy individuals for transfusion to recipients
with decreased immunity or who are leukopenic.
Leukapheresis is also used in leukemia patients who have
too many white cells. The procedure leads to temporary
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