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thyrotoxicosis 704 tissue-specific antigen
follicles, causing them to release thyroid hormones.
This stage is soon replaced by hypothyroidism in the
later stages of Hashimoto’s thyroiditis. Patients with this
disease have enlarged thyroid glands. Circulating autoantibodies
against thyroglobulin and thyroid microsomal
antigen (thyroid peroxidase) are present. Cellular sensitization
to thyroid antigens may also be detected. Thyroid
hormone replacement therapy is given for the hypothyroidism
that develops.
thyrotoxicosis
Disease of the thyroid characterized by hyperthyroidism
with elevated levels of thyroid hormones in the blood and
thyroid gland hyperplasia or hypertrophy. Thyrotoxicosis
may be autoimmune, as in Graves’ disease, in which diffuse
goiter may be observed. Autoantibodies specific for thyroid
antigens mimic thyroid-stimulating hormones (TSHs) by
stimulating thyroid cell function. In addition, patients with
Graves’ disease develop ophthalmopathy and proliferative
dermopathy. The disease occurs predominantly in females
(70 females to 1 male) and usually appears in the 30- to
40-year old age group. In Caucasians, it is a disease associated
with DR3. Patients may develop nervousness, tachycardia,
and other symptoms of hyperthyroidism. They also
have increased levels of total and free T3 and T4 along with
a diffuse and homogeneous uptake of radioactive iodine.
Three types of antithyroid antibodies occur: (1) thyroidstimulating
immunoglobulin, (2) thyroid growth-stimulating
immunoglobulin, and (3) thyroid binding-inhibitory
immunoglobulin. Their presence confirms a diagnosis
of Graves’ disease. The thyroid gland may be infiltrated
with lymphocytes. Long-acting thyroid stimulator (LATS)
is classically associated with thyrotoxicosis. It is an IgG
antibody specific for thyroid hormone receptors. It induces
hyperactivity by combining with TSH receptors.
thyrotropin
Thyroid-stimulating hormone (TSH).
thyrotropin receptor autoantibodies
Autoantibodies specific for thyrotopin receptor (TSHR) are
very heterogeneous. Some TSHR antibodies stimulate the
receptor and are associated with Graves’ disease (hyperthyroidism).
Others are inhibitory. Thyrotopin-binding inhibitory
immunoglobulin (TBII) antibodies bind to TSHR and
inhibit binding of TSH to receptors. Thyroid-stimulating
antibodies (TSAbs) mimic TSH and induce thyroid cells to
increase cAMP production in a bioassay. Long-acting thyroid
stimulator (LATS), a growth-promoting immunoglobulin
(IgG) found in Graves’ disease, interacts with TSHR.
TSHR antibodies are measured by receptor assays. TS
antibodies are 95% in Graves’ disease and correlate closely
with disease activity. TSB antibodies are associated closely
with atrophic gastritis and severe hypothyroidism, yet atrophic
thyroiditis may occur in their absence. TBII and TS
Bantibodies occur in nongoiterous autoimmune thyroiditis.
Placental passage of TSHR antibodies may induce transient
hypo- or hyperthyroidism.
thyroxine
A hormone synthesized and released by the thyroid gland
that regulates cell metabolism, body temperature, use of
energy, and normal functioning of the central nervous and
cardiovascular systems.
TI antigen
Abbreviation for T-independent (Td) antigen.
TI-1 antigen, TI-2 antigen
Refer to thymus-independent antigen.
tight junction
Juncture between the apical poles of epithelial cells that
blocks the passive diffusion of pathogenic microorganisms,
macromolecules, and peptides but can be unblocked by
cytokine signaling.
tight skin 1 (Tsk1) mouse
A mouse strain developed from a spontaneous dominant
mutation in the inbred B10.D2(58N)/Sn strain that represents
a genetically transmitted model of systemic sclerosis.
The effects of the Tsk1 mutation include excessive accumulation
of collagen in the dermis and various internal organs,
thereby mimicking major aspects of human systemic
sclerosis. The principal visceral changes in Tsk1/+ occur in
the lungs and heart. Lungs are greatly distended and histologically
resemble human emphysema with little fibrosis.
Alveolar spaces are markedly dilated with thin disrupted
walls and subpleural cysts and bullae. Myocardial hypertrophy
with increased collagen deposition is present.
tight skin 2 (Tsk2) mouse
A mouse strain with features resembling those of both
human systemic sclerosis and the original tight skin mutation
of the mouse, Tsk1.
TIL
Abbreviation for tumor-infiltrating lymphocyte.
tine test
A human tuberculin test involving intradermal inoculation
of dried, old tuberculin using a four-pointed applicator that
introduces the test substance 2 mm below the surface.
tingible body
Nuclear debris present in macrophages of lymph node,
spleen, tonsil germinal centers, and the dome of the appendix.
tingible body macrophages
Phagocytic cells that engulf apoptotic B cells. They form in
large numbers at the height of a germinal center response.
TIR domain
Toll/IL-1R domain present in Toll-like receptor cytoplasmic
tails, IL1R, and selected plant pattern recognition molecules.
Possesses no intrinsic tyrosine kinase activity but
acquires the MyD88 adaptor protein.
Tiselius, Arne W. K. (1902–1971)
Swedish chemist educated at the University of Uppsala,
where he also conducted research. In 1934, he was at the
Institute for Advanced Study in Princeton, and in 1946 he
worked for the Swedish National Research Council. He was
awarded the Nobel Prize in Chemistry in 1948 and became
president of the Nobel Foundation in 1960. With Elvin A.
Kabat, he perfected the electrophoresis technique and classified
antibodies as γ globulins. He also developed synthetic
blood plasmas.
tissue-fixed macrophage
Histiocyte.
tissue-specific antigen
An antigen restricted to cells of one type of tissue. Tissuespecific
or organ-specific autoantibodies occur in certain
types of autoimmune diseases. Organ-specific or tissuespecific
antibodies are often not species-specific. For
example, autoantibodies against human thyroglobulin may
cross react with the corresponding molecules of other species.
The antigen may be a protein or carbohydrate epitope
present only in a particular tissue or subcellular site. When