Webster's New World Medical Dictionary

T cell, CD8+
See 
T lymphocyte, cytotoxic.
T cell, CD4+
See 
T-4 cell.
T cell, peripheral
A T cell that is found in the
peripheral blood rather than in the lymphatic
system.
T cell lymphoma
A disease in which cells in the
lymphoid system called T cells (or T lymphocytes)
become malignant. T cell lymphomas account for a
minority (about 15 percent) of non-Hodgkin lym-
phomas in the US, with the remainder comprised of
malignancies of B lymphocytes. See also 
lym-
phoma; non-Hodgkin’s lymphoma.
T lymphocyte, cytotoxic
A cell that expresses the
CD8 transmembrane glycoprotein and is antigen spe-
cific. Abbreviated CTL. CTLs are able to search out
and kill specific types of infected or abnormal cells.
When they find cells carrying the peptide they are
looking for, they induce those cells to secrete pro-
teins that attract nearby macrophages (specialized
white blood cells). These macrophages then sur-
round and destroy the targeted cells. CTLs are partic-
ularly important in the immune response to viruses
and cancer. Also known as TC cell. See also 
CD8; T
cell; T-suppressor cell.
tabes dorsalis
See 
neurosyphilis, tabes.
tablespoon
An old-fashioned but convenient
household measure of capacity that is equal to
about 15 cc of liquid.
TACE
Transarterial chemoembolization, a proce-
dure in which the blood supply to a tumor is
blocked (embolized) and chemotherapy is adminis-
tered directly into the tumor. For example, TACE has
been used to treat some liver cancers.
tache noire
French for “black spot,” to describe
a small ulcer covered with a black crust at the site
of a tick bite. A tache noire is characteristic of sev-
eral tick-borne rickettsial diseases. See also 
rick-
ettsial diseases.