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schlepper 638 scratch test
schlepper
Landsteiner’s term for large macromolecules that serve as
carriers for simple chemical molecules serving as haptens.
The immunization of rabbits and other animals with a
hapten–carrier complex leads to the formation of antibodies
specific for the hapten and the carrier. T cells were later
shown to be carrier-specific and B cells hapten-specific.
Carriers are conjugated to haptens through covalent linkages
such as the diazo linkage.
Schultz–Dale test (historical)
Strong contraction of the isolated uterine horn muscle
of a virgin guinea pig that has been actively or passively
sensitized occurs following the addition of specific antigen
to a 37°C tissue bath in which it is suspended. This reaction
is the basis for an in vitro assay of anaphylaxis termed the
Schultz–Dale test. Muscle contraction is caused by the
release of histamine and other pharmacological mediators
of immediate hypersensitivity following antigen interaction
with antibody fixed to tissue cells.
SCID (severe combined immunodeficiency)
Refer to severe combined immunodeficiency syndrome.
SCID (severe combined immunodeficiency, human–mouse)
A murine immunodeficiency in which human immune system
elements such as bone marrow and thymic fragments
have been introduced. Pluripotent human hematopoietic
stem cells differentiate into mature immunocytes in these
mice, rendering them useful for investigating lymphocyte
development.
SCID (severe combined immunodeficiency, mouse)
An autosomal-recessive mutation expressed as severe
combined immune deficiency in the CB-17Icr mouse
strain. These mice do not have serum immunoglobulins,
yet their adenosine deaminase (ADA) levels are normal.
They lack T and B lymphocytes and thus fail to respond
to T cell-dependent or -independent antigens when challenged.
Likewise, their lymph nodes and spleen cells fail
to proliferate following challenge by T or B lymphocyte
mitogens. The lymphoid stroma in their lymph nodes and
spleen is normal. Even though they exhibit no evidence of T
cell-mediated immunity, they have natural killer (NK) cells
and mononuclear phagocytes that are normal in number and
function. The mutation likewise does not affect myeloid and
erythroid lineage cells. B cell development is arrested at the
pro-B stage before cytoplasmic or surface immunoglobulins
are present. Normal numbers of macrophages are present
in the spleen, peritoneum, and liver. The SCID mutation is
associated with an intrinsic defect in lymphoid stem cells.
The main characteristic of SCID mice is the failure of their
lymphocytes to express antigen-specific receptors due to
disordered rearrangements of T cell receptors or immunoglobulin
genes. The defect in recombination of antigenspecific
receptor genes may be associated with the absence
of a DNA recombinase specific for lymphocytes in these
mice. Attributable to a defect in DNA-PK function requisite
for V(D)J recombination. This mouse model may be used
to substitute for human experimentation to investigate the
effects of anti-HIV drugs and immunostimulants. It is also
useful for investigations of neoplasms in hosts lacking
effective immune responses.
Scl-70 antibody
An antinuclear antibody found in as many as 70% of
patients with diffuse-type scleroderma (progressive
systemic sclerosis) who experience extensive and rapid skin
involvement and early visceral manifestations.
Scl-70 (topoisomerase I) autoantibodies.
Scl-70 (topoisomerase I) autoantibodies
Autoantibodies found in 20 to 40% of diffuse scleroderma
patients. Two thirds of patients with these autoantibodies
have diffuse scleroderma and 20% of patients with limited
scleroderma manifest topoisomerase I autoantibodies. Sc1-70
autoantibodies or DR3-DRw52a tissue types represent a
17-fold increase in risk for development of pulmonary fibrosis
in scleroderma. These autoantibodies are occasionally found
in classical systemic lupus erythematosus (SLE) without
manifestations of scleroderma. Topoisomerase I autoantibodies
portend a poor prognosis in Raynaud’s phenomenon.
Silica can induce a scleroderma-like condition. Some patients
develop Scl-70 autoantibodies. The preferred technique for
detection of IgG autoantibodies against topoisomerase I is
enzyme immunoassay (EIA) with immunoblot confirmation.
The relevance of an association of topoisomerase I autoantibodies
with neoplasms remains to be determined.
scleroderma
Refer to progressive systemic sclerosis.
SCM-1
Single cysteine motif 1 (SCM-1) is a member of the γ (C)
family of chemokines. cDNA clones derived from human
peripheral blood mononuclear cells stimulated with phytohemagglutinin
(PHA) encode SCM-1, which is significantly
related to the α and β chemokines. It has only the second
and fourth of four cysteines conserved in these proteins. It
is 60.5% identical to lymphotactin. SCM-1 and lymphotactin
are believed to represent human and mouse prototypes
of a γ (C) chemokine family. SCM-1 is expressed by human
T cells and spleen.
sCR1 (soluble complement receptor type 1)
A substance prepared by recombinant DNA technology that
combines with activated C3b and C4. This facilitates their
inactivation by complement factor I. sCR1 significantly
diminishes myocardial injury induced by hypoxia in rats.
scratch test
Skin test for the detection of immunoglobulin E (IgE) antibodies
against a particular allergen that are anchored to mast
cells in the skin. After scratching the skin with a needle, a
minute amount of aqueous allergen is applied to the scratch
site, and the area is observed for the development of urticaria