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R5 viruses
CCR5-binding HIV strains that infect both macrophages
and CD4 + T cells. Previously known as M-tropic viruses.
RA
Rheumatoid arthritis.
RA-33
A rheumatoid arthritis-specific antigen that is identical to
the heterogeneous rhnRNP-A2 ribonucleoprotein.
Rabbit immunity.
rabbit immunity
The rabbit immune system is similar to that of the human
with only minor variations. Rabbit gut-associated lymphoid
tissue (GALT) consists of an appendix, Peyer’s patches,
and diffuse lymphatic nodules. GALT and other peripheral
lymphoid tissues of rabbits contain a permanent lymphatic
system with lymph nodes. The rabbit has a prominent
spleen and a thymus that undergoes involution in adulthood.
Lymphopoiesis originates in the bone marrow, and
the maturing cells occupy appropriate tissues and organs.
Rabbit leukocytes resemble those of other mammalian
mononuclear phagocyte systems. Lymphoid cell populations
and circulation routes resemble those of other mammals,
making rabbits excellent models for immunological investigations.
Rabbit cytokines include migration inhibition factor
(MIF), chemotactic factor, migration stimulation factor
(MSF), interleukin-1 (IL1), IL2, and tumor necrosis factor
(TNF-α). IgM, IgG, IgE, and IgA immunoglobulins and
several groups of allotypes have been discovered in rabbits.
The rabbit major histocompatibility complex (MHC) has
both class I and class II regions. B and T cells, microphages,
and polymorphonuclear leukocytes have been described.
Rabies virus.
R
rabies
An infection produced by an RNA virus following a bite
from an infected animal. The virus passes across the neuromuscular
junction and infects a nerve, from which it reaches
the central nervous system. It also reaches salivary glands of
lower animals. The virus infection leads to cerebral edema,
congestion, round cell infiltration of the spinal cord and
gray matter in the brain stem, and profound loss of Purkinje
cells. Negri bodies are found prominently in the medulla
oblongata, hippocampus, and cerebellum. Clinically, the fury
associated with the disease is due to irritability of the central
nervous system and is accompanied by fever, hyperethesia,
and anoxia aggression. The infection may be paralytic.
Human rabies is rare in the United States; it is more common
in other animals, with most cases in skunks and raccoons.
Fewer cases occur in bats, and only 2% each in dogs and cats.
The virus is transmitted among humans by inhalation or by
corneal transplantation, but not by human bites.
rabies vaccination
Refer to post-rabies vaccination encephalomyelitis.
rabies vaccine
A pre-exposure immunizing preparation that contains
killed rabies virus, used primarily for individuals who
face rabies as an occupational risk. Following the bite of a
rabid animal, both the vaccine and rabies immune globulin
containing preformed antibodies are administered. In
humans, significant levels of neutralizing antibody can be
generated by immunization with a virus grown in tissue
culture in diploid human embryo lung cells. A vaccine
adapted to chick embryos, especially egg passage material,
is used for prophylaxis in animals prior to exposure. The
vaccine originally prepared by Pasteur made use of rabbit
spinal cord preparations to which the virus became adapted.
These preparations were discontinued because of the risk of
inducing post-rabies vaccination encephalomyelitis.
Rac
A small guanine nucleotide-binding protein that the guanosine
diphosphate (GDP)–guanosine triphosphate (GTP) exchange
factor Vav activates during the early stages of T lymphocyte
activation. GTP-Rac activates a protein kinase cascade that
leads to activation of the stress-activated protein (SAP) kinase,
c-Jun N-terminal kinase (JNK), and p38 kinase, which are
similar to the mitogen-activated protein (MAP) kinases.
RA cell
Abbreviation for rheumatoid arthritis cell.
radial immunodiffusion
A technique used to ascertain the relative concentration of an
antigen. Antigen is placed in a well and permitted to diffuse
into agar containing an appropriate dilution of an antibody.
The area of the precipitin ring that encircles the well in the
equivalence region is proportional to the antigen concentration.
radiation and immunity
Ionizing radiation injures DNA and other cellular constituents.
The most radiosensitive cells in the body are the
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