Accuracy The ability of a test for an analyte to give
results comparable to the true value. Compare with
precision.
Achlorhydria Low or absent secretion of acid in the
stomach.
Acquired immunity The development of true immu-
nity arising from aspecific immune responseto an
immunogen.
Actinomycosis A fungal infection that may occur follow-
ing injuries to oral tissues and causes inflammation.
Acute Diseases or clinical events that have a rapid, often
severe onset, but of short duration (compare with
chronic).
Acute intravascular hemolysis Hemolysis that results
from an incompatible blood transfusion, particularly
involving the ABO blood group system.
Acute phase proteins A set of plasma proteins associated
with anacute phase response, for example C-reactive
protein and fibrinogen.
Acute phase response A systemic response involving
changes in the composition of the blood, including an
increased neutrophil count and increase in amount
of theacute phase proteins, which occur in certain
clinical conditions such as trauma, infections, necro-
sis, tumors and other inflammatory events.
Acute rejection of an allograft is one that occurs usually
within a few weeks following the transplant.
Agammaglobulinemia (Or hypogammaglobulinemia)
clinical conditions in which theF-class ofimmuno-
globulinsis deficient.
Agglutination The clumping together of blood cells.
Aging Most widely understood to be the decrease in the
ability to survive on growing older.Alleles Different forms of the same gene. Any one indi-
vidual will normally have two alleles for each gene,
one from each parent, since, in general, chromosomes
occur in matching or homologous pairs where each
member of a pair contains an allele.Allergens These are immunogens that cause an allergy.Allergy A term often used to describe a Type I hypersen-
sitivity, which results in inflammation on exposure to
an allergen.Allogeneic Transplants that involve donors and recipients
who are genetically nonidentical (see alsoautologous
andsyngeneic).Allograft A transplant between two genetically dif-
ferent people (see also isograft and xenogeneic
transplants).Allotopic expression A technique whereby a mitochon-
drial gene is inserted into the nucleus where it is
transcribed to produce a product that is imported
into the mitochondria where it alleviates the effects of
a mtDNA mutation.Alternative pathway Activation of complement proteins
in the absence of antibody by cell wall components of
bacteria and yeasts.Amenorrhea An absence or stopping of the men-
strual cycle. Compare with galactorrhea and
oligomenorrhea.Analytes Substances that are measured to assist diagnosis
and monitor the treatment of disease.GLOSSARY
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