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lymphocytotoxin 468 lymphoid tissues
diseases such as systemic lupus erythematosus (SLE) and
rheumatoid arthritis (RA). The sera of most SLE patients
react with CD45 on mitogen-stimulated T lymphocytes;
some interact with T cell receptor and β 2 microglobulin,
and selected B cell antigens. Alloantibodies against lymphocytes
usually result from immunization, blood transfusion,
transplantation, and pregnancy. IgG alloantibodies
are warm-reactive (at 37ºC or room temperature). Major
histocompatibility complex (MHC) class I and class II
antigens on lymphocyte surfaces are the targets of lymphocyte
autoantibodies. The microlymphocytotoxicity test
is the method of choice for lymphocytotoxic autoantibody
detection.
lymphocytotoxin
Refer to lymphotoxin.
lymphocytotrophic
Possessing a special attraction or affinity for lymphocytes.
Examples include the attraction of the Epstein–Barr virus
for B lymphocytes and the affinity of human immunodeficiency
virus (HIV) for helper/ inducer (CD4) T
lymphocytes.
lymphogranuloma venereum (LGV)
A sexually transmitted disease induced by Chlamydia
trachomatis that is divided into L 1, L 2, and L 3 immunotypes.
It is rare in the United States but endemic in Africa,
Asia, and South America. Clinically, patients develop
papule ulcers that heal spontaneously at the inoculation site.
This is followed by development of inguinal and perirectal
lymphadenopathy, as well as skin sloughing, hemorrhagic
proctocolitis, purulent draining, fever, headache, myalgia,
aseptic meningitis, arthralgia, conjunctivitis, hepatitis,
and erythema nodosum. Various antibody assays used in
the diagnosis of LGV include complement fixation, with
a titer >1:32, and immunofluorescence. The Frei test,
which consists of the intracutaneous inoculation of a crude
antigen into the forearm, is also used and can be read after
72 hours. It is considered positive if the area of induration
exceeds 6 mm.
lymphoid
Tissues such as lymph nodes, thymus, and spleen that contain
large populations of lymphocytes.
lymphoid cell
A cell of the lymphoid system. The classic lymphoid cell is
the lymphocyte. A cell that arises from a common lymphoid
progenitor, including T and B lymphocytes, NK cells, and
NKT cells.
lymphoid cell series
(1) Cell lineages whose members morphologically resemble
lymphocytes, their progenitors, and their progeny.
(2) Organized tissues of the body in which the predominant
cell type is the lymphocyte or cells of the lymphoid cell
lineage. These include the lymph nodes, thymus, spleen,
and gut-associated lymphoid tissue, among others.
lymphoid enhancer factor-1(LEF-1)
A cell-type specific transcription factor and member of
the family of high motility group (HMG) domain proteins
that recognizes a specific nucleotide sequence in the T
cell receptor (TCR) α enhancer. The function of LEF-1 is
dependent in part on the HMG domain that induces a sharp
bend in the DNA helix and on an activation domain that
stimulates transcription only in the specific context of other
enhancer-binding proteins.
lymphoid follicles
Organized aggregates of lymphocytes. Refer to the lymphoid
nodules.
lymphoid lineage
Lymphocytes of all varieties and the bone marrow cells that
are their precursors.
lymphoid nodules (or follicles)
Aggregates of lymphoid cells present in the loose connective
tissue supporting the respiratory and digestive membranes.
They are also present in the spleen and may develop beneath
any mucous membrane as a result of antigenic stimulation.
They are poorly defined at birth. Characteristic lymphoid
nodules are round and nonencapsulated. They may occur as
isolated structures or may be confluent, such as in the tonsils,
pharynx, and nasopharynx. In the tongue and pharynx, they
form a characteristic structure referred to as Waldeyer’s ring.
In the terminal ileum, they form oblong areas called Peyer’s
patches. The lymphoid nodules contain B and T cells and
macrophages. Plasma cells in submucosal sites synthesize
immunoglobulin A (IgA), which is released in secretions.
lymphoid organs
Organized lymphoid tissues in which numerous lymphocytes
interact with nonlymphoid stroma. The thymus and bone
marrow are the primary lymphoid organs where lymphocytes
are formed. The principal secondary lymphoid tissues
where adaptive immune responses are initiated include the
lymph nodes, spleen, and mucosa-associated lymphoid tissues,
including the tonsils, Peyer’s patches, and appendix.
lymphoid patches
Unencapsulated clusters of lymphoid follicles.
lymphoid progenitor cell
A cell belonging to the lymphoid lineage, such as a bone
marrow stem cell that gives rise to all lymphocytes.
lymphoid system
The lymphoid organs and the lymphatic vessels.
Tonsil
Thymus
Lymph
nodes
Spleen
Lymph
nodes
Bone
Lymphoid tissues.
lymphoid tissues
Lymphocyte-containing tissues that include the lymph
nodes, spleen, thymus, Peyer’s patches, tonsils, bursa of