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RNA polymerase (RNAP) I, II, and III autoantibodies 628 Romer reaction (historical)
Anti-RNA polymerase autoantibody.
RNA polymerase (RNAP) I, II, and III autoantibodies
RNAP I antibodies found in 4% of systemic sclerosis
patients show speckled or punctate nucleolar staining
patterns. Autoantibodies are also found in the urine of
46% of patients with systemic lupus erythematosus (SLE)
and in 19% of patients with rheumatoid arthritis (RA).
Autoantibodies against RNAP I, II, and III are specific
for systemic sclerosis (SSc), especially diffuse cutaneous
SSc. Clinically, these autoantibodies are associated with
increased frequency of heart and kidney involvement and
poor 5-year survival. Twenty-three percent of SSc sera
contain antibodies against RNAP III, which is a marker
for SSc with diffuse or extensive cutaneous involvement.
Autoantibodies against RNAP I are present in 4 to 33% of
SSc patients and in subjects with SLE or overlap syndromes.
Autoantibodies against RNAP II are frequently
accompanied by autoantibodies against RNAP I and III.
RNAse protection assay
A technique to detect and quantify messenger RNA
(mRNA) copies of specific genes based on nRNA hybridization
to radiolabeled RNA probes followed by digestion of
the unhybridized RNA with RNAse. Double-stranded RNA
duplexes formed as a result of hybridization are resistant to
RNAse degradation. Their size depends on the probe length.
Gel electrophoresis is used for their separation, and radioautography
is employed for their detection and quantification.
RNA splicing
The method whereby nontranslatable RNA sequences
(introns) are excised from the primary transcript of a split
gene. The translatable sequences (exons) are united to produce
a functional gene product.
Ro/SSA and La/SSB
Heterogeneous ribonucleoprotein complexes that consist of
antigenic proteins (two principal proteins of 52 kDa [Ro52]
and 60 kDa [Ro60] for Ro/SSA and one protein of 48 kDa
for La/SSB) associated with small cytoplasmic RNAs
(hY-RNAs). Antibodies to Ro/SSA and La/SSB antigens
are found frequently in the sera of patients with primary
Sjögren’s syndrome.
rocket electrophoresis
The electrophoresis of antigen into an agar-containing
specific antibody. Through electroimmunodiffusion, lines
of precipitation formed in the agar by the antigen–antibody
interaction assume the shape of a rocket. The antigen concentration
can be quantified because the size of the rocket-like
area is proportional to the antigen concentration. This can
Antigen
concentration
–
Precipitin arc
(rocket)
+
Antigen well
Rocket electrophoresis.
Agarose gel
with antibody
be deduced by comparing with antigen standards. This technique
has the advantage of speed. It can be completed within
hours instead of longer periods required for single radial
immunodiffusion. Also called Laurell rocket electrophoresis.
Rodgers (Rg) antigens
Epitopes of C4d fragments of human complement component
C4. They are not intrinsic to erythrocyte membranes.
The Chido epitope is found on C4d from C4B, whereas
the Rodgers epitope is found on C4A derived from C4d.
The Rodgers epitope is Val–Asp–Leu–Leu, and the Chido
epitope is Ala–Asp–Leu–Arg. They are situated at residue
positions 1188 to 1191 in the C4d region of the C4 α chain.
Antibodies against Ch and Rg antigenic determinants
agglutinate saline suspensions of red blood cells coated
with C4d. Because C4 is found in human serum, anti-Ch
and anti-Rg are neutralized by the sera of most individuals
that contain the relevant antigens. Ficin and papain destroy
these antigens.
Ivan Roitt (left) with Deborah Doniach (right).
Roitt, Ivan
Roitt, Deborah Doniach, and other colleagues observed a
positive precipitation reaction following interaction of sera
from Hashimoto’s thyroiditis patients and human thyroglobulin
in vitro. This represented the first proof that humans
with thyroid disease had circulating antibodies reactive
with thyroglobulin.
Romer reaction (historical)
Romer in 1909 described erythematous swelling following
intracutaneous injection of diphtheria toxin in small quantities.
The reaction was found to be neutralized by homologous
antitoxin. The smallest amount of diphtheria toxin that