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hinovirus immunity 626 ricin
rhinovirus immunity
Although most rhinovirus infections resolve spontaneously,
respiratory tract infections may occur in immunocompromised
hosts. There are nearly 100 serotypes of rhinovirus.
Studies with human rhinovirus 2 (HRV-2) reveal that HRV-2specific
immunoglobulins in sera and nasal secretions increase
1 to 2 weeks after inoculation. HRV-2 antibodies peak at 35
days after inoculation. Serum neutralizing antibodies remain
elevated for many years following infection. Local specific
antibodies cannot be detected after 2 years. Preinoculation
IgA levels in nasal washings are diminished in those who
become infected compared with those who do not. Aspirin
and acetaminophen suppress serum antibody responses.
RhLA locus
The major histocompatibility locus in the rhesus monkey.
Rh null
Human erythrocytes that fail to express Rh antigens due
to the homozygous inheritance of the Xr gene that causes a
regulator-type defect or the inheritance of an amorphic ( –/– )
gene. The Rh null phenotype is associated with diminished
erythrocyte survival.
rhodamine isothiocyanate
A reddish-orange fluorochrome used to label immunoglobulins
and other proteins for immunofluorescence studies.
Rh oD immune globulin
Prepared from the serum of individuals hyperimmunized
against Rh oD antigen. It is used to prevent the immunization of
Rh – mothers by Rh oD + erythrocytes of babies, especially at parturition
when the babies’ red cells enter the maternal circulation
in significant quantities, and at other times during pregnancy,
such as after a trauma that might introduce fetal blood into the
maternal circulation. This prevents hemolytic disease of the
newborn in subsequent pregnancies. The dose used is effective
in inhibiting immune reactivity against 15 mL of packed
Rh o(D) + red blood cells. It should be administered within 72
hours of parturition. It may also be used following inadvertent
or unavoidable transfusion of RhD + blood to RhD – recipients,
especially women of childbearing age.
Rh oGAM
Refer to Rh o(D) immune globulin.
RIA
Radioimmunoassay.
HOCH 2
O
H 2 N C
OH
ribavirin (1--5-d-ribofuranosyl-
1,2,4-triazole-3 carboxamide)
A substance that interferes with mRNA capping of certain
viruses, thereby restricting the synthesis of viral proteins. It
is used in aerosol form to treat severe respiratory syncytial
virus infection in children.
O
N
OH
Ribavirin.
N
N
ribosomal autoantibodies
Autoantibodies against ribosomal constituents that are
specific to systemic lupus erythematosus (SLE) and occur
only rarely in other rheumatic diseases. P (phospho)
proteins (P0, P1, and P2) are the most common antigens.
These P proteins are also known as A (alanine-rich)
proteins. Antibodies to P proteins that are specific for a
common carboxyl terminus epitope occur in 12 to 19%
of SLE patients. Other ribosomal antigens include L12
protein, L5/5s, S10, Ja, L7, and ribosomal ribonucleoprotein
(rRNA). Anti-L7, anti-rRNA, anti-S10, and anti-Ja
autoantibodies are more common than those against L12
and L5/5S, which are rare. Immunoblotting techniques
reveal autoantibodies to ribosomal proteins in about 42%
of SLE and 55% of rheumatoid arthritis (RA) sera. The
clinical significance of ribosomal antibodies remains to be
determined.
ribosomal P protein (RPP) autoantibodies
Autoantibodies found in 45 to 90% of patients with systemic
lupus erythematosus (SLE) with severe depression or
psychosis; they are also present in 7 to 20% of SLE patients
who are not psychotic. A positive RPP autoantibody test is
not diagnostic of lupus psychosis, as approximately 50% of
patients with RPP autoantibodies do not have severe behavioral
problems. These antibodies are found in Sjögren’s
syndrome patients with central nervous system (CNS)
abnormalities. RPP autoantibodies are rare in systemic sclerosis
and when present indicate an overlap with SLE. The
clinical significance of these autoantibodies is doubtful.
Firm data suggest that RPP autoantibodies may play a role
in the pathogenesis of lupus hepatitis.
ribosome
A subcellular organelle in the cytoplasm of a cell that is a site
of amino acid incorporation in the process of protein synthesis.
ribozyme
A catalytic RNA segment with the ability to break and form
covalent bonds. It combines specifically with and cleaves
mRNAs with a complementary sequence, thereby functioning
as molecular shears. Employed in treatment to block the
expression of selected proteins.
Richet, Charles Robert (1850–1935)
Parisian physician who became a professor of physiology
at the University of Paris. He was interested in the physiology
of toxins and, with Portier, discovered anaphylaxis,
for which he was awarded the Nobel Prize in Physiology
or Medicine in 1913. They discovered anaphylaxis in dogs
exposed to the toxins of murine invertebrates to which
they had been previously sensitized and thus demonstrated
an immune-type reaction that was harmful rather than
protective. Experimental anaphylaxis was later shown to be
similar to certain types of hypersensitivity, lending clinical
and theoretical significance to their discovery. (Refer to
L’anaphylaxie, 1911.)
ricin
A toxic protein found in seeds of Ricinus communis (castor
bean) plants. It is a heterodimer composed of a 30-kDa α
chain that mediates cytotoxicity and a 30-kDa β chain that
interacts with cell surface galactose residues that facilitate
passage of molecules into cells in endocytic vesicles. Ricin
inhibits protein synthesis by linkage of dissociated α chains
in cytosols to ribosomes. The ricin heterodimer or its α chain
conjugated to a specific antibody serves as an immunotoxin.