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spectrotype 664 splenic cords
spectrotype
In isoelectric focusing analysis, the arrangement of bands
in a gel that is characteristic for a single protein or category
of proteins. An antibody spectrotype on an isoelectric
focusing gel may signify that it is the product of a particular
antibody-synthesizing clone.
sperm antibodies
Antibodies specific for the heads or tails of sperm. These
antibodies are synthesized by 3% of infertile males and 2 to
9% of infertile females. The titer of antibody against sperm
and infertility are positively correlated. Treatment includes
corticosteroid therapy or the use of a condom to permit
waning of immunologic memory in the female or washing
of sperm prior to insemination.
sperm autoantibodies
Antibodies against human sperm can be formed in both
sexes and play a role in infertility. Not all antibodies against
spermatozoa interfere with sperm function and fertilization.
Antibodies in cervical mucus or on sperm are associated
with a reduction in cervical mucus penetration. Vasectomy
causes the production of sperm autoantibodies. In vasectomized
men, immunoglobulin A (IgA) sperm antibodies
on all sperm and a heightened immune response (antibody
titer >1:256) are associated with conception failure. Assays
for circulating sperm antibodies vary in sensitivity and
specificity. The variables to be considered include class of
immunoglobulin and different sperm antigens, among others.
Of the various methods to measure sperm antibodies,
the direct immunobead test (dIBT) is the method of choice.
It is based on rosette formation by viable sperm and plastic
beads coated with antiserum to human immunoglobulins
and allows measurement of class-specific antibodies (IgG,
IgM, or IgA) and antibody attachment sites (heads or tails).
Antibodies can be measured in cervical mucus, seminal
plasma, serum, and in an antibody complex on the surfaces
of donor sperm. The measurement of sperm antibodies on
sperm is the preferred technique. Three major sperm surface
glycoproteins have been identified. Sperm antibodies
include those reactive with galactosyl transferase.
spheroplast
A Gram-negative bacterial protoplast that contains outer
membrane remains.
spherulin
An antigen derived from spherules of Coccidioides
immitis used for the delayed-type hypersensitivity skin
test for coccidioidomycosis.
Spleen, gross specimen.
Spleen follicle with central follicular artery.
spleen
An encapsulated organ in the abdominal cavity that has
important immunologic and nonimmunologic functions.
Vessels and nerves enter the spleen at the hilum, as in
lymph nodes, and travel part of their course within the
fibrous trabeculae that emerge from the capsule. The
splenic parenchyma has two regions that are functionally
and histologically distinct. The white pulp consists of a
thick layer of lymphocytes surrounding the arteries that
have left the trabeculae. They form periarterial sheaths
that contain mainly T cells. The sheaths then expand along
their course to form well developed lymphoid nodules
called malpighian corpuscles. The red pulp consists of a
mesh of reticular fibers, continuous with the collagen fibers
of the trabeculae. These fibers enclose an open system
of sinusoids that drain into small veins and are lined by
endothelial cells with reticular properties. The endothelium
is discontinuous, leaving small slits through which cells
must pass during transit. Within the sinusoidal mesh are
red blood cells, macrophages, lymphocytes, and plasma
cells. The red pulp between adjacent sinusoids forms
pulp cords, sometimes called the cords of Billroth. The
marginal zone consists of a poorly defined area between
the white and red pulp where the periarterial sheath and
lymphoid nodules merge. The blood vessels branch, and at
the periphery of the marginal zone the blood empties into
the pulp. Lymphocytes of the marginal zone are mainly
T cells. They surround the periphery of the lymphoid
nodules that comprise B cells. In this marginal region, the
T and B cells contact each other. Some B cells may convert
into immunoblasts. Further maturation to plasma cells
occurs in the red pulp. Active follicles contain germinal
centers in which lymphoblasts may be generated. They are
discharged into sinusoids, and plasma cells may form. The
spleen also contains dendritic cells that have long cytoplasmic
extensions and serve as antigen-presenting cells, interacting
with lymphocytes. The spleen filters blood as the
lymph nodes filter the lymph. The spleen is active in the
formation of antibodies against intravenously administered
particulate antigens. It has numerous additional functions,
including the sequestration and destruction of senescent
red blood cells, platelets, and lymphocytes.
splenic cords
A network of collagen that encircles accumulations of
erythrocytes, reticular cells, fibroblasts, macrophages, and
lymphocytes in the spleen.