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eagin (historical) 614 recombinant inbred strains
by antioxidants (ascorbic acid, vitamin E, uric acid, glutathione)
and cellular enzymes (superoxide dismutase, catalase,
glutathione peroxidase). During oxidative stress, these protective
mechanisms are overwhelmed, leading to membrane
damage, protein modifications, and apoptosis.
reagin (historical)
(1) Obsolete term for a complement-fixing IgM antibody
reacting in the Wassermann test for syphilis. (2) An earlier
name for immunoglobulin E (IgE), the anaphylactic antibody
in humans that fixes to Fcε receptors on tissue mast cells,
leading to the release of histamine and vasoactive amines
following interaction with a specific antigen (allergen).
reaginic antibodies
Refer to reagin.
reassortant vaccine
An immunizing preparation prepared by combining
antigens from several viruses or from several strains of the
same virus.
Rebuck skin window.
Rebuck skin window
A clinical method for assessing chemotaxis in vivo by making
a superficial abrasion of the skin and covering it with
a glass slide. The slide is removed several hours later, air
dried, and stained for leukocyte content.
receptor
A molecular configuration on a cell surface or macromolecule
that combines with molecules that are complementary
to it. Examples include enzyme–substrate reactions, T cell
receptors, and membrane-bound immunoglobulin receptors
of B cells. A receptor is usually a transmembrane molecule
that binds to a ligand on a cell surface, leading to biochemical
changes within the cell.
receptor-associated tyrosine kinases
Molecules of the Src family with which lymphocyte antigen
receptors associate. They bind to the tails of receptors
through their SH2 domains.
receptor blockade
The rendering of a B cell anergic as a consequence of
interaction of its receptors with large quantities of antigen
without cross linking. This diminishes tyrosine kinase activation
associated with receptors, which inhibits signaling.
receptor editing
A mechanism whereby rearranged genes in B lineage cells
may undergo secondary rearrangement, forming different
antigenic specificities. The process involves recombination-activating
gene (RAG) reactivation, additional light
chain V–J recombinations, and new immunoglobulin (Ig)
light-chain synthesis, permitting cells to express a different
immunoglobulin receptor that does not react with self.
A B cell whose receptors react with self antigen during
development in the bone marrow is provided a narrow
window of opportunity to rearrange its light chain gene to
prevent apoptosis through alteration of its specificity for
antigen as the new light chain replaces the self-reactive one.
receptor-mediated endocytosis
Internalization into endosomes of cell surface receptorbound
molecules, such as B cell receptors, to which
antigens are bound and internalized. The interaction of a
soluble macromolecule to its corresponding cell surface
receptor leads to internalization through clathrin polymerization.
When a clathrin-coated pit is invaginated, the
receptor and bound macromolecule are enclosed in a
clathrin-coated vesicle subjected to the endocytic processing
pathway.
recessive lethal gene
A hereditary unit required for humans and other animals to
reach adulthood. Death in utero or soon after birth results
when both copies are defective.
recirculating pool
The continuous recirculation of T and B lymphocytes
between the blood and lymph compartments.
recirculation of lymphocytes
The continuous transport of lymphocytes from the blood
to secondary lymphoid tissues to lymph and back into the
blood. Traffic to the spleen represents an exception, as lymphocytes
only enter and exit the spleen via the blood.
recognition phase
The first event in an adaptive immune response when antigen-specific
lymphocytes bind to antigens. This phase often
occurs in secondary lymphoid tissues such as lymph nodes
or spleen where antigens and naïve lymphocytes are present.
recognition unit
Clq facilitates recognition unit binding to cell surface
antigen–antibody complexes. To launch the classical complement
cascade, Clq must link to two immunoglobulin G
(IgG) antibodies through their Fc regions. By contrast, one
pentameric IgM molecule attached to a cell surface may
interact with Clq to initiate the classical pathway. Binding
of Clq activates Clr to become activated Clr*. This, in turn,
activates Cls.
recombinant DNA
The physical union of two or more strands of available
DNA to form another DNA strand. The term describes the
exchange of DNA during meiosis, mitosis, or gene conversion.
It may also refer to DNA strands produced in vitro.
recombinant DNA technology
The technique of isolating genes from one organism and
purifying and reproducing them in another, often accomplished
through ligation of genomic or cDNA into a plasmid
or viral vector where DNA replication takes place.
recombinant inbred strains
Inbred strains of F 2 generation mice developed by crossing
two inbred strains to yield F 1 and then F 2 generations.
Progeny of the F 2 generation are inbred until they become
homozygous at most loci. The progeny approach complete
genetic identity and homozygosity. Recombination occurs
during meiosis and consists of crossing over and recombination
of parts of two chromosomes. Recombinant inbred
strains help to establish genetic linkages. These genetically
uniform and homozygous mice offer a means to study the
consequences of reassorting various parental genes such as
heavy chain genes.