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Raji cell assay for CIC 611 rapamycin
After combination of Raji cells with a serum sample, the
immune complex is bound and quantified using radiolabeled
F(ab′) 2 fragments of antibodies against IgG.
Raji cell assay for CIC
One of the least analytically sensitive and least diagnostically
specific assays for circulating immune complexes
(CICs). Positive results may signify the presence of lymphocyte
antibodies, particularly in systemic lupus erythematosus
(SLE). Patients with systemic necrotizing vasculitis may
appear positive in Raji assays for CICs. This assay has also
been used to monitor sarcoidosis patients.
Ramon, Gaston (1886–1963)
French immunologist who perfected the flocculation assay
for diphtheria toxin.
Ramon test (historical)
A rough method for assaying the activity of a preparation of
diphtheria (or tetanus) toxin. Varying quantities of antitoxin
are combined with a constant quantity of toxin in vitro. The
tubes are placed in a 44 to 46°C water bath and observed
often. The test is read by noting the tube in which flocculation
occurs first. This is the point of equivalence where
antitoxin has neutralized the homologous toxin. This assay
is based on the antigenicity of the toxin with which the
antitoxin combines, in contrast to toxicity. Thus, it measures
combining power and provides an indirect idea of toxicity
only insofar as toxicity and antigenicity are positively correlated.
Because they are not always closely correlated, this
method is less reliable than the in vivo technique of Ehrlich
that measures the actual toxic effect of the toxin and the
ability of the antitoxin to combat it. The Ramon test measures
toxin in L f (flocculating) units. An L f unit is defined as
the amount of toxin that flocculates most rapidly with one
unit of antitoxin. The L f value, in contrast to other L values
described, must be calculated. To determine the L f value for
a toxin, the following formula is used.
L f /mL toxin = ([antitoxin units/mL] × [mL antitoxin]) ÷ (mL of toxin)
Thus, the L f content of a toxin may be determined if the following
values are known: (1) antitoxin units per milliliter of
antitoxin, (2) milliliter of antitoxin required for most rapid
flocculation with toxin, and (3) milliliter of toxin employed.
Although the Ramon flocculation test was classically used to
determine the L f value of toxin, it may be carried out in reverse
to assay the antitoxin units in each milliliter of antitoxin not
previously standardized. The same formula is applicable:
L f /mL toxin = ([antitoxin units/mL] × [mL antitoxin]) ÷ (mL toxin)
Antitoxin units/mL = ([L f /mL toxin] × [mL toxin]) ÷ (mL antitoxin)
Varying quantities of toxin of known L f value are combined
with a constant amount of antiserum. The tube in which
flocculation first occurs is the point of equivalence; therefore,
the amount of toxin in a milliliter is substituted into
the formula together with the known values that include the
L f per milliliter of toxin and the number of milliliters of
antitoxin held constant. By simple arithmetic, the antitoxin
units per milliliter may then be calculated. In this quantitative
precipitin test, antibody dilutions are varied and antigen
dilutions remain the same. The first tube where precipitation
occurs is considered the end point.
RANA (rheumatoid arthritis-associated nuclear antigen)
An antigen of Epstein–Barr virus (EBV)-immortalized
lymphoid cell lines that reacts with sera from patients with
rheumatoid arthritis.
RANA (rheumatoid arthritis-associated nuclear antigen)
autoantibodies
Patients with rheumatoid arthritis (RA) develop antibodies
to Epstein–Barr virus (EBV)-related antigens that include
viral capsid antigen, early antigen, EBV nuclear antigen,
and rheumatoid arthritis nuclear antigen. RANA antibodies
are present in approximately 60% of RA patients, as
revealed by incomplete Freund’s adjuvant (IFA) or enzyme
immunoassay (EIA) techniques using synthetic peptide
P62, which is the equivalent of the principal epitope of
RANA. The clinical significance of RANA antibodies
remains to be determined.
random breeding
The mating of members of a population at random. The
genetic diversity arising from random breeding depends
on the size of the population. If it is large, genetic diversity
will be maintained. If it is small, genetic uniformity will
result in spite of random breeding.
RANTES
An 8-kDA protein comprised of 68-amino acid residues.
It belongs to the platelet factor-4 (PF-4) superfamily of
chemoattractant proteins. RANTES chemoattracts blood
monocytes and CD4 + /CD45RO + T cells in vitro and is useful
in research on inflammation. A chemokine of the β (CC)
family, RANTES was first identified by molecular cloning as
a transcript expressed in T cells but not B cells. It is the only
β chemokine in platelets and demonstrates powerful chemotactic
and activating properties for basophils, eosinophils, and
natural killer (NK) cells. It has a human immunodeficiency
virus (HIV)-suppressive effect and acts synergistically with
macrophage inflammatory peptide 1α (MIP-1α) and MIP-1β
in the suppression of HIV. Tissue sources include T lymphocytes,
monocytes, epithelial cells, mesangial cells, platelets,
and eosinophils, among other cell types. Monocytes, T lymphocytes,
basophils, eosinophils, natural killer (NK) cells,
dendritic cells, and mast cells are targets.
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rapamycin
Refer to sirolimus. To achieve clinical immunosuppression,
rapamycin is effective at one eighth the concentration required
for FK506 and at 1% of levels required for cyclosporine.
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Structure of rapamycin.
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