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RB200 613 reactive oxygen species (ROS)
characterized by severe pallor and often accompanied by pain
and paresthesias. It is brought on by cold, emotional stress,
or anatomic abnormality. When the condition is idiopathic or
primary, it is called Raynaud’s disease. Raynaud’s phenomenon
is seen in several connective tissue diseases including systemic
lupus erythematosus and systemic sclerosis. Subjects with cryoglobulinemia
may also manifest the phenomenon.
RB200
Refer to lissamine rhodamine.
RCA
Regulator of complement activation.
RCA (regulator of complement activation) locus
A locus on the long arm of chromosome 1 with a 750-kb
DNA segment containing genes that encode complement
receptor 1, complement receptor 2, C4-binding protein, and
decay-accelerating factor. These substances regulate the
activation of complement through combination with C4b,
C3b, or C3dg. A separate chromosome 1 gene, not in the
RCA locus, encodes factor H.
reactation
The resumption of replication of an infectious agent following
reactivation of a latent infection that leads to a productive
infection that results in disease symptoms.
a
Anti-a
reaction of identity
Double immunodiffusion in two dimensions in gel can
reveal that two antigen solutions are identical. If two
antigens are deposited into separate but adjacent wells and
permitted to diffuse toward a specific antibody diffusing
from a third well that forms a triangle with the other two, a
continuous arc of precipitation is formed. This reveals the
identity of the two antigens.
reaction of nonidentity
Double immunodiffusion in two dimensions in gel can
reveal that two antigen solutions are nonidentical. If both
a
Reaction of identity.
a
Anti-a, d
d
Reaction of nonidentity.
antigen solutions are deposited into separate but adjacent
wells and permitted to diffuse toward a combination of
antibodies specific for each antigen diffusing from a third
well that forms a triangle with the other two, the lines
of precipitation form independently of one another and
intersect, resembling crossed swords. This reaction reveals
a lack of identity (no epitopes shared) between the antigens
detectable by these antibodies.
x
Spur
Anti-y
Reaction of partial identity.
reaction of partial identity
Double immunodiffusion in two dimensions in gel can
reveal that two antigen solutions share epitopes but are
not identical. If each antigen is deposited into separate but
adjacent wells and permitted to diffuse toward specific antibodies
diffusing from a third well that forms a triangle with
the other two, a continuous arc of precipitation manifesting
a spur is formed. This demonstrates that the two antigens
share some epitopes (shown by the continuous arc) but not
others (demonstrated by the spur).
reactive arthritis
Arthritis in the knees, feet, and sacroiliac region attributable
to autoimmunity that occurs 1 to 4 weeks following an
acute bacterial infection.
reactive lysis
Dissolution of red blood cells not sensitized with antibody.
Initiated by C5b and C6 complexes in the presence of C7,
C8, and C9. The activation of complement leads to lysis as a
“bystander” phenomenon.
reactive nitrogen intermediates
Very cytotoxic antimicrobial substances produced when
oxygen and nitrogen combine within phagocytes such as
neutrophils and macrophages.
reactive oxygen intermediates (ROIs)
Free radicals derived from nitrogen, including nitric oxide,
that destroy microorganisms within phagosomes. Highly
reactive compounds that include superoxide anion (O 2), singlet
oxygen, hydroxyl radicals (OH), and hydrogen peroxide
(H 2O 2) produced in cells and tissues. Phagocytes use ROIs
to form oxyhalides that injure ingested microorganisms.
Release from cells may induce inflammatory responses
leading to tissue injury. Also known as reactive oxygen
species (ROS).
reactive oxygen species (ROS)
Oxygen-derived radicals generated in the mitochondria as
oxygen is reduced along the electron transport chain. These
can be produced by phagocytic cells to kill pathogens, but
are also involved in signaling in other cell types. Examples of
ROS are nitric oxide (NO); hydroxyl radicals (OH-); and peroxides
(H 20 2). Damage from these toxic species is prevented
y
R