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LATS (long-acting thyroid stimulator) 442 L chain
agglutinated by rheumatoid factor (anti-immunoglobulin
antibody) that may be detected in the serum of a patient
with rheumatoid arthritis.
LATS (long-acting thyroid stimulator)
See long-acting thyroid stimulator.
LATS protector
An antibody found in Graves’ disease patients that inhibits
LATS neutralization in vitro. It forms the basis for a LATS
protector assay in which sera from patients with Graves’
disease are tested for the ability to “protect” a known
LATS serum from neutralization by binding to human
thyroid antigen.
Antigen Antibody
(a)
(d)
Antigen–antibody lattice formation.
Antibody
Antigen
Haptene
Antibody
lattice theory
The concept that soluble antigen and antibody combine
in a precipitation reaction to produce an interconnecting
structure of molecules. This structure has been likened to
a crisscross pattern of wooden strips fastened together to
reveal a series of diamond-shaped structures. Lattice formation
requires interaction of bivalent antibodies with multivalent
antigens to produce a connecting linkage of many
molecules that constitute a complex whose density becomes
sufficient to settle out of solution. The more epitopes recognized
by the antibody molecules present, the more extensive
the complex formation.
(b)
Marrack’s proposal of a lattice network theory of antigen–antibody
interaction.
(e)
(c)
(f)
Laurell crossed immunoelectrophoresis
Refer to crossed immunoelectrophoresis.
Laurell rocket test
A method to quantify protein antigens by rapid immunoelectrophoresis.
Antiserum is incorporated in agarose, into
which wells are cut and protein antigen samples are distributed.
The application of an electric current at 90° angles to
the antigen row drives antigen into the agar. Dual lines of
immune precipitate emanate from each well and merge to
form a point where no more antigen is present, producing
a structure that resembles a rocket. The amount of antigen
can be determined by measuring the rocket length from the
well to the point of precipitate. This length is proportional
to the total amount of antigen in the preparation.
LAV
Lymphadenopathy-associated virus. Refer to HIV-1.
Lawrence, Henry Sherwood (1916–2004)
American immunologist. While studying type IV hypersensitivity
and contact dermatitis, he discovered transfer
factor. (See Cellular and Humoral Aspects of Delayed
Hypersensitivity, 1959.)
lazy leukocyte syndrome
A disease of unknown cause in which patients experience
increased incidence of pyogenic infections such as abscess
formation, pneumonia, and gingivitis. The disease is linked
to defective neutrophil chemotaxis in combination with
neutropenia. Random locomotion of neutrophils is diminished
and abnormal, demonstrated by the vertical migration
of leukocytes in capillary tubes. The exodus of neutrophils
from the bone marrow is also impaired.
LCA (leukocyte common antigen)
See leukocyte common antigen.
LCAM
Leukocyte cell adhesion molecule.
L cell conditioned medium
A powerful growth factor for macrophages, termed macrophage
colony-stimulating factor (M-CSF), present in
L cell cultures.
L chain
A 22-kDa polypeptide chain found in all immunoglobulin
molecules. The two types are designated κ and λ. Each
four-chain immunoglobulin monomer contains two κ or two
λ light chains. The two types of light chains never occur in
one molecule under natural conditions. Refer to light chain.
Structure of TCR/CD3 complex showing the lck, fyn, and ZAP phosphotyrosine
kinases.