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athymic nude mouse 81 atypical pANCA
Athymic nude mouse.
athymic nude mouse
A mouse strain with no thymus and no hair. T lymphocytes
are absent; therefore, no manifestations of T cell
immunity are present; that is, the mice do not produce
antibodies against thymus-dependent antigens and fail to
reject allografts. They possess normal complements of B
and natural killer (NK) cells. These nude or nu nu mice are
homozygous for a mutation (v on chromosome 11) inherited
as an autosomal-recessive trait. These features make
the strain useful in studies evaluating thymic-independent
immune responses.
atopic
Adjective referring to clinical manifestations of type I
(IgE-mediating) types of hypersensitivity to environmental
antigens such as pollen or house dust resulting in allergic
rhinitis (hay fever), asthma, eczema, or food allergies.
Individuals with such allergies are described as atopic.
atopic allergy or atopy
A genetically determined increased tendency of some members
of the population to develop immediate hypersensitivity
reactions, often mediated by immunoglobulin E (IgE)
antibodies, against innocuous substances.
atopic dermatitis
Chronic eczematous skin reaction marked by hyperkeratosis
and spongiosis, especially in children with genetic predispositions
to allergy. The dermatitis is often accompanied
by elevated serum immunoglobulin (IgE) levels that are not
proved to produce the skin lesions. A type I hypersensitivity.
atopic hypersensitivity
Refer to atopy.
atopic rhinitis
An inflammatory reaction in the nasal mucous membranes
attributable to type I hypersensitivity to an inhaled allergen.
Clinical features include nasal secretions, itchy and tearing
eyes. Also called hay fever.
atopy
A type of immediate (type I) hypersensitivity to common
environmental allergens in humans mediated by humoral
antibodies of the immunoglobulin (IgE) class, formerly
termed reagins, that are able to passively transfer the effect.
Atopic hypersensitivity states include hay fever, asthma,
eczema, urticaria, and certain gastrointestinal disorders.
There is a genetic predisposition to atopic hypersensitivities
that affect more than 10% of the human population. Antigens
that sensitize atopic individuals are termed allergens and
include (1) grass and tree pollens; (2) dander, feathers, and
hair; (3) eggs, milk, and chocolate; and (4) house dust,
Atopic dermatitis.
bacteria, and fungi. IgE antibody is a skin-sensitizing homocytotropic
antibody that occurs spontaneously in the sera of
human subjects with atopic hypersensitivity. IgE antibodies
are nonprecipitating (in vitro), heat-sensitive (destroyed by
heating to 60°C for 30 to 60 minutes), unable to pass across
the placenta, remain attached to local skin sites for weeks
after injection, and fail to induce passive cutaneous anaphylaxis
(PCA) in guinea pigs.
ATRA
Abbreviation for all trans-retinoic acid. A therapeutic agent
administered orally that blocks the action of the chimeric
protein in acute promyelocytic leukemia and restores
hematopoietic cell maturation.
attenuate
To diminish the virulence of a pathogenic microorganism,
rendering it incapable of causing disease. Attenuated
bacteria or viruses may be used in vaccines to induce better
protective immunity than would have been induced with a
killed vaccine.
attenuated
Diminished virulence of a microorganism.
attenuated pathogen
A pathogen that has been altered to the point that it will
grow in a host and induce immunity without causing clinical
illness.
attenuation
Decrease of a particular effect, such as by exposing a
pathogenic microorganism to suboptimal culture conditions
or chemical or genetic alterations that diminish or negate its
virulence but leave its antigenicity or immunogenicity intact.
AtxBm
Abbreviation for a so-called B cell mouse—a thymectomized
irradiated adult mouse that has received a bone
marrow transplant.
atypical pANCA
Atypical antineutrophil cytoplasmic antibodies (ANCAs)
are present in patients with ulcerative colitis (UC), primary
sclerosing cholangitis (PSC), and autoimmune hepatitis
(AIH). Atypical pANCA reacts with nuclear envelope
proteins and neutrophils. Immunoblotting has revealed
reactivity to a myeloid-specific 50-kDa nuclear protein with
an isoelectric point of pH 6.0 found in 92% of patients with
inflammatory bowel or hepatobiliary disease and atypical
A