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Strongyloides immunity 670 superantigen
Strongyloides immunity
Immunoglobulin G (IgG), IgA, and IgE classes form in
response to antigens of Strongyloides stercoralis filariform
larvae. The principal humoral responses of the IgG 4
subclass may be directed to more than 50 different 15- to
100-kDa antigens. The remaining IgG subclasses recognize
fewer than 20 antigens. Zinc endopeptidase together with
31- and 28-kDa proteins are antigens that induce specific
immune responses, but they are not protective against dissemination
in the host. Patients without detectable humoral
responses remain asymptomatic. Immunocompromised
patients with disseminated infection may manifest high
titers of parasite-specific antibodies. Impaired cellmediated
immunity has been claimed by some to facilitate
parasite dissemination, but this has not been proven,
especially as patients with acquired immune deficiency
syndrome (AIDS) have not developed this as an opportunistic
infection.
STS
Abbreviation for serological test for syphilis.
St. Vitus dance (chorea)
Involuntary muscular twitching movements that may occur
in acute rheumatic fever.
subacute sclerosing panencephalitis
A slow virus disease that occurs infrequently as a complication
of measles and produces progressively destructive injury
to the brain through slow replication of defective viruses.
subexon
A small exon possessing splice donor and acceptor sites that
is spliced at the RNA level with other small subexons to
produce a complete constant exon in the Igh locus.
subset
A subpopulation of cells such as T lymphocytes in samples
of peripheral blood. Subsets are identified by immunophenotyping
with monoclonal antibodies and by flow
cytometry. The cells are separated based on their surface
CD (cluster of differentiation) determinants, such as CD4,
which identifies helper/inducer T lymphocytes, and CD8,
which identifies suppressor/cytotoxic T lymphocytes.
substance P (SP)
A tachykinin that may induce joint inflammation when
released at local sites. It facilitates synthesis by monocytes
of interleukin-1 (IL1), IL6, and tumor necrosis factor α
(TNF-α) and stimulates synovial cells to produce prostaglandins.
Its receptor is designated NK1. Substance P is a
principal component of the neuroimmune axis and axon
reflex. It is a mediator of neurogenic inflammation, causing
vasodilatation and plasma extravasation. It induces histamine
release from mast cells; lymphocyte proliferation;
immunoglobulin and cytokine secretion from B lymphocytes
and monocytes, respectively; macrophage stimulation;
immune complex formation; eosinophil peroxidase
secretion; and chemotaxis in response to platelet-activating
factor (PAF). SP induces polymorphonuclear leukocyte
(PMNL) chemotaxis, phagocytosis, respiratory burst activity,
exocytosis, and antibody-mediated cell cytotoxicity. It
elevates superoxide production in PMNLs and facilitates
TNF-dependent IL8 secretion. SP derived from primary
afferent nerves has a proinflammatory effect on neutrophils,
leading to increased adhesion to bronchial epithelial cells
in acute and chronic bronchitis. SP levels are increased in
the sputum of asthmatic and chronic bronchitis patients and
those with nasal allergies. It increases PMNL infiltration
into the skin in allergic contact dermatitis and enhances
PGD 2 and leukotriene C4 release from human nasal mucosa
and skin mast cells. In vessels, SP induces intercellular
adhesion molecule 1 (ICAM-1) expression on vascular
endothelial cells. It induces degranulation of mast cells and
facilitates transendothelial migration.
substrate adhesion molecules (SAMs)
Extracellular molecules that share a variety of sequence
motifs with other adhesion molecules. Most prominent are
segments similar to the type III repeats of fibronectin and
immunoglobulin-like domains. In contrast to other morphological
regulatory molecules, SAMs do not have to be made
by the cells that bind them. SAMs can link and influence
the behavior of one another. Examples include glycoproteins,
collagens, and proteoglycans.
subunit vaccine
An immunizing preparation comprised of a specific component
of a pathogen, such as a viral protein or bacterial
polysaccharide. The vaccine employs whole micromolecules
or large macromolecular fragments that contain the
protective epitopes.
sugar cane worker’s lung
Refer to bagassosis and farmer’s lung.
suicide, immunological
The use of an antigen deliberately labeled with high-dose
radioisotope to kill a subpopulation of lymphocytes with
receptors specific for that antigen following antigen binding.
sulfite sensitivity
Sulfites or sulfiting agents (such as sulfur dioxide, bisulfite
salt, and metabisulfite salt) broadly used as food additives
that can induce reactions marked by angioedema, laryngeal
edema, asthma, and anaphylaxis. Sulfite reactions occur in
atopic and selected nonatopic patients but are more commonly
observed in chronic asthma. The hyperreactivity to
sulfur dioxide generated from sulfites is believed to involve
afferent cholinergic receptors in the tracheobronchial tree,
IgE-mediated reactions in a few patients, and sulfite oxidase
deficiency. Kinins are believed to play a role in mediation
of bronchial constriction. Treatment includes cromolyn to
stabilize mast cells; atropine to block cholinergic sensitivity;
and cyanocobalamin to assist sulfite oxidation in sulfite
oxidase-deficient patients. Diagnosing sulfite sensitivity is
based on metabisulfite challenge.
Sulzberger–Chase phenomenon
The induction of immunological unresponsiveness to skinsensitizing
chemicals such as picryl chloride by feeding an
animal (e.g., guinea pig) the chemical in question prior to
application to the skin. Intravenous administration of the
chemical may also block the development of delayed-type
hypersensitivity when the same chemical is later applied
to the skin. Simple chemicals such as picryl chloride may
induce contact hypersensitivity when applied to the skin
of guinea pigs. The unresponsiveness may be abrogated by
adoptive immunization of a tolerant guinea pig with lymphocytes
from one that has been sensitized by application
of the chemical to the skin without prior oral feeding.
superantigen
An antigen such as a bacterial toxin that is capable of stimulating
multiple T lymphocytes, especially CD4 + T cells, leading
to the release of relatively large quantities of cytokines.
A protein that unites simultaneously with an invariant site