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lapinized vaccine 441 latex particles
cells express both class I and class II histocompatibility
antigens, as well as C3b receptors and IgG Fc receptors on
their surfaces. They function as antigen-presenting cells.
Epidermal Langerhans cells express complement receptors 1
and 3, Fcγ receptors, and fluctuating quantities of CD1. They
are important in the development of delayed-type hypersensitivity
through the uptake of antigen in the skin and its
transport to the lymph nodes. Dendritic cells do not express
Fcγ receptors or CD1. Langerhans cells in the lymph nodes
are found in the deep cortex. Veiled cells in the lymph are
indistinguishable from Langerhans cells.
lapinized vaccine
A preparation used for immunization that is attenuated by passage
through rabbits until its original virulence has been lost.
LAR
Refer to local acquired resistance.
large granular lymphocytes (LGLs)
Refer to natural killer cells.
large lymphocyte
A 12-μm or greater diameter lymphocyte.
large pre-B cells
Immature B cells with surface pre-B cell receptors that are
deleted on transition to small pre-B cells, which undergo
light chain gene rearrangement.
large pyroninophilic blast cell
Cells that stain positively with methyl green pyronin stain.
They are found in thymus-dependent areas of lymph nodes
and other peripheral lymphoid tissues.
LAT
Refer to linker of activation in T cells.
late onset immune deficiency
A disease of unknown cause associated with gastric carcinoma,
pernicious anemia, atrophic gastric autoimmunity,
and several other conditions.
late phase reaction (LPR)
An inflammatory response that begins approximately 5
to 8 hours after exposure to antigen in immunoglobulin E
(IgE)-mediated allergic diseases. Leukocytes, attracted to
the allergen site by early phase reaction mediators, produce
cytokines, enzymes, and inflammatory mediators that cause
further injury. Eosinophils are the predominant NANT
cell type. Inflammation is accompanied by pruritus and
minor cellular infiltration. Asthmatic patients may produce
delayed or secondary responses following antigenic challenge
involving the release of histamines from neutrophils.
This induces secondary degranulation of mast cells and
basophils which stimulates bronchiole hyperreactivity.
Whereas prostaglandin and then PGD 2 are produced in the
primary response, they are not formed in the late phase
reaction. Cold air, ozone, viruses, and other irritants may
induce the late phase reaction. This condition may be
treated with β-adrenergic aerosols; it is resistant to treatment
with antihistamine. Repeated episodes of late phase
reactivity can produce tissue injury.
late pro-B cell
Refer to pro-B cell.
latency
A condition in which viruses enter a cell but do not replicate.
Once reactivated, the virus may replicate and cause disease.
latent allotype
The detection of an unexpected allotype in an animal’s
genetic constitution. This allotype is expressed as a
temporary replacement of the nominal heterozygous
allotype of the animal. It has been described among rabbit
immunoglobulin allotypes. Whereas an F 1 rabbit would
be expected to synthesize α 1 or α 2 heavy chain allotypes
if one parent were homozygous for α 1 and its other parent
homozygous for α 2, the F 1 rabbit might under certain
circumstances of stimulation produce immunoglobulin
molecules of the α 3 (latent) allotype.
latent infection
The long-term presence of a pathogenic microorganism that
remains uninfectious and fails to produce clinical symptoms.
A consequence of viral genome integration into host
cell DNA or altered expression of viral genes.
latex allergy
Hypersensitivity to natural latex, the milky sap from the rubber
tree Hevea brasiliensis. The symptoms range from hand
dermatitis to life-threatening anaphylaxis. Three percent of the
general population shows sensitivity to latex and 2 to 25% of
healthcare workers manifest this type of hypersensitivity; 9%
of nurses have natural latex-specific immunoglobulin E (IgE)
antibodies. Patients with increased frequency of operations
have increased prevalence of the allergy (29%). The number of
operations and total serum IgE are the most important factors
in predicting latex allergy. Natural latex-specific IgE is detectable
by RAST, enzyme immunoassay (EIA), flow cytometry,
and electrochemiluminescence. Patients with latex allergy
show increased frequency of allergy to foods such as avocado,
potato, banana, tomato, chestnut, and kiwi.
Antigen
Adsorption
Passive
agglutination
Latex carrier
Latex fixation test.
Antibody
latex fixation test
A technique in which latex particles are used as passive
carriers of soluble antigens adsorbed to their surfaces.
Antibodies specific for the adsorbed antigen then cause
agglutination of the coated latex particles. This technique
is widely used and is the basis of a rheumatoid arthritis
(RA) test in which pooled human immunoglobulin G (IgG)
molecules are coated on the surfaces of latex particles that
are then agglutinated by anti-immunoglobulin antibodies in
the sera of rheumatoid arthritis patients.
latex particles
Inert particles of defined size that serve as carriers of
antigens or antibodies in latex agglutination immunoassays.
An example is the rheumatoid arthritis (RA) test
in which latex particles are coated with pooled human
IgG that serves as the antigen. The coated particles are
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