Untitled - D Ank Unlimited

-1 antichymotrypsin
A histiocytic marker. By immunoperoxidase staining, it is
demonstrable in tumors derived from histiocytes. It may
also be seen in various carcinomas.
-1 antitrypsin (A1AT)
A glycoprotein in circulating blood that blocks trypsin,
chymotrypsin, and elastase, among other enzymes. The
gene on chromosome 14 encodes 25 separate allelic forms
that differ according to electrophoretic mobility. The PiMM
phenotype is physiologic. The PiZZ phenotype is the most
frequent form of the deficiency, which is associated with
emphysema, cirrhosis, hepatic failure, and cholelithiasis,
with an increased incidence of hepatocellular carcinoma. It
is treated with prolastin. Adenoviruses may be employed to
transfer the A1AT gene to lung epithelial cells, after which
A1AT mRNA and functioning A1AT become demonstrable.
abatacept
A recombinant fusion protein comprised of the extracellular
domain of cytotoxic T-lymphocyte-associated antigen 4
(CTLA-4) fused with human IgG Fc. CTLA-4 is a costimulatory
molecule of T cells that unites with CD80 and CD86
on antigen presenting cells. A selective costimulation
modulator, abatacept blocks activation of T cells by binding
to CD80 and CD86, thereby interfering with the interaction
with CD28, a costimulatory signal requisite for full T
lymphocyte activation, implicated in the pathogenisis of
rheumatoid arthritis (RA). Activated T cells are present in
the synovial of RA patients. In vitro, abatacept diminishes
T cell proliferation and blocks the synthesis of the cytokines
TNF-α, interferon-γ, and IL-2. In a rat arthritis model,
abatacept diminishes inflammation, decreases anti-collagen
antibody production, and reduces antigen-specific synthesis
of interferon-γ. It is used for the treatment of severe rheumatoid
arthritis.
A blood group
Refer to ABO blood group system.
ABO blood group antigen
Glycosphingolipid epitopes on erythrocytes and numerous
other types of cells. These antigens are governed by alleles
that encode enzymes needed for their synthesis. They differ
among individuals and may serve as alloantigens that lead
to hyperacute rejection of allografts and to blood transfusion
reactions.
chain
The immunoglobulin (Ig) class-determining heavy chain
found in IgA molecules.
adalimumab
A human IgG 1 molecule used in the treatment of rheumatoid
arthritis that blocks the interaction of TNF-α with TNF
receptors on cell surfaces but fails to bind with TNF-β.
It diminishes levels of C-reactive protein, erythrocyte
sedimentation rate, IL-6 in serum, and matrix metalloproteinases
MMP-1 and MMP-3. In vitro, it causes lysis of cells
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that express TNF-α when complement is present. It has a
serum half-life of 2 weeks. Adalimumab binds specifically
to TNF-α and inhibits its interaction with the p55 and p75
cell surface TNF receptors. It lyses surface cells in vitro
in the presence of complement. It fails to bind or inactivate
lymphotoxin (TNF-β). TNF is a naturally occurring
cytokine that is involved in inflammatory and immune
responses. Levels are elevated in synovial fluid in rheumatoid
arthritis and psoriatic arthritis, where it plays a significant
part in the inflammatory reaction and joint destruction
that are hallmarks of the disease.
α-Fetoprotein.
-fetoprotein
A principal plasma protein in the α globulin fraction
present in the fetus. It bears considerable homology with
human serum albumin. It is produced by the embryonic
yolk sac and fetal liver and consists of a 590-amino acid
residue polypeptide chain structure. It may be elevated in
pregnant women bearing fetuses with open neural tube
defects, central nervous system defects, gastrointestinal
abnormalities, immunodeficiency syndromes, and various
other abnormalities. After parturition, the high levels
in fetal serum diminish to levels that cannot be detected.
α-fetoprotein induces immunosuppression, which may
facilitate neonatal tolerance. Based on in vitro studies, it is
believed to facilitate suppressor T lymphocyte function and
diminish helper T lymphocyte action. Liver cancer patients
reveal significantly elevated serum levels of α-fetoprotein.
In immunology, however, it is used as a marker of selected
tumors such as hepatocellular carcinoma. It is detected by
the avidin–biotin–peroxidase complex (ABC) immunoperoxidase
technique using monoclonal antibodies.
heavy chain disease
A rare condition in individuals of Mediterranean extraction
who may develop gastrointestinal lymphoma and malabsorption
with loss of weight and diarrhea. The aberrant
plasma cells infiltrating the lamina propria of the intestinal
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