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DIARECT Newsletter No. 2/2008
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Dear Madame or Sir, |
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During
the last couple of months our R&D team has been striving quite hard
to bridge the diagnostic gap in autoantibody monitoring of PBC
patients. Besides the M2 antigen constituents (namely PDC-E2,
BCOADC-E2, and OGDC-E2) we were proud to introduce the Sp100 antigen
just a few months ago. Sp100 antibodies are responsible for the
well-known multiple nuclear dot pattern (MND-ANA), seen in 10-15% of
PBC and mainly associated with sicca syndrome. Now we have placed the
last piece in the diagnostic puzzle with the introduction of the
nucleoporin gp210 antigen as a further supplementary target for PBC
in-vitro diagnostics. The nuclear membrane associated antibodies
(NM-ANA) occur in about 25-50% of PBC patients, even in a number of M2
negative cases.
Furthermore, we wish to direct your attention to a new international
comparative study focussing on the diagnostic relevance of
conventionally purified (thus bovine) vs. human recombinant SS-A/Ro60
autoantigens. These results were presented on the occasion of the 6th
International Congress on Autoimmunity, held September 10-14, 2008, in
Porto, Portugal. The very clear conclusion of this study showed the
highest degree of comparability of recombinant vs. native SS-A/Ro60
antigen and, moreover, documented the superb quality of a new
line-assay device based on DIARECT's recombinant human Ro60.
Last but not least, November is Medica time and we are looking forward
to meet with many clients and partners in Düsseldorf to discuss current
and future projects. But November this year is more than just the
exciting Medica show: DIARECT is going to celebrate its 10th
anniversary on November 26, 2008. A very good opportunity to say "Thank
You" to all our customers, vendors, collaboration partners and friends
all over the world. Without your constant support and trust in our
business we never would have become what we are now. We aim to assist
you further in the future with outstanding products and unsurpassed
service.
Pleasant reading!
Your DIARECT team
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PBC Associated Antibodies Targeted to the Nuclear Membrane: the Nuclear Pore Protein gp210 |
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Although
M2 antibodies (AMA) are considered the hallmark diagnostic feature of
primary biliary cirrhosis (PBC), they are not the only disease-specific
autoantibodies; a number of additional nuclear autoantigens have been
identified within the nuclear pore protein one of which, gp210, is
particularly predominant (1). The nucleoporin, gp210, is a 210-kDa
transmembrane glycoprotein believed to be involved in the attachment of
pore complex constituents with the nuclear membrane and, in addition,
acts as an essential trafficking regulator in the eukaryotic nuclear
pore complex (2).
Antibodies directed against nucleoporin gp210 are found in about 25% of
patients with M2/AMA-positive PBC and up to 50% of those with
M2-negative PBC. Indirect immunofluorescence can be used, but only
well-trained and highly experienced experts are able to discern those
three antibody patterns (M2, Sp100, gp210) by immunofluorescence with
HEp-2 cells. All three IIF photographs have an underlying M2/AMA
positivity. In Fig 1a you can see an additional gp210 (rimlike ANA)
pattern, whereas Fig. 1b shows the well-known multiple nuclear dot ANA
of Sp100. An even more challenging situation is shown in Fig. 1c with a
combination of all three entities: M2, gp210, and Sp100. The disease
specificity for the detection of gp210 autoantibodies is close to 100%,
but in contrast to M2 antibodies they have a profound prognostic
significance and may be associated with more active and severe disease
and therefore poor prognosis (3, 4).
DIARECT now has a recombinant gp210 available. This antigen has been
optimally designed for high-level expression of the immunogenetically
relevant epitopes in the Baculovirus/insect cell system. This assures
highest sensitivity and specificity for the development of first-rate
diagnostic tests. Together with recombinant Sp100 and M2 antigens,
gp210 now completes a panel of qualitatively outstanding PBC targets
for the detection of autoantibodies in patients with PBC (Fig. 2).
We would like to thank Prof. R.-L. Humbel (LLIP, Luxembourg) for
critically evaluating the gp210 antigen and providing us with IIF
photographs.
References
- Gershwin, M.E., Ansari, A.A., Mackay, I.R. et al. (2000) Immunological Reviews 174, 210-25
- Greber, U.F., Senior, A., Gerace,L. (1990) EMBO J. 9, 1495-502
- Itoh, S., Ichida, T., Yashida, T. (1998) J. Gastroenterol. Hepatol. 13, 257-65
- Bogdanos, D.P., Liaskos, C., Pares, A. et al. (2007) Hepatology 45, 1583
| 18000 | M2 | 0.1 mg | | 18001 | M2 | 1.0 mg | | 18900 | Sp100 | 0.1 mg | | 18901 | Sp100 | 1.0 mg | | 19000 | gp210 | 0.1 mg | | 19001 | gp210 | 1.0 mg |
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Figure 1. The
detection by indirect immunofluorescence (IIF) of circulating
antibodies in the serum of patients with PBC. 1a: M2-negative and
gp210-positive; 1b: M2-negative and Sp100-positive; 1c: gp210, Sp100
and M2 positive
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Figure 2. Dot blot analysis of sera from patients with PBC. Click on image for a larger version.
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Evaluation of Recombinant Ro60 for Diagnostic use in AI-Line ELISA |
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J. Schulte-Pelkum1, M. Fritzler2, M. Szmyrka-Kaczmarek3, M. Petschinka1, T. Simon4, M. Mahler1
1Dr. Fooke Laboratorien GmbH, Development, Neuss, Germany, 2University of Calgary, Faculty of Medicine, Calgary, Canada,3Wroclaw University of Medicine, Wroclaw, Poland, 4DIARECT AG, Freiburg, Germany
Autoantibodies to SS-A/Ro60 are found in patients
with systemic autoimmune rheumatic diseases (SARD) such as systemic
lupus erythematosus (SLE), systemic sclerosis (SSc) and Sjögren
syndrome (SjS). Until today, native Ro60 (nRo60) has been reported to
be a superior analyte when compared to recombinant Ro60 (rRo60) for the
detection of anti-Ro60 aab. A newly available rRo60 antigen was tested
in two studies and compared to nRo60.
Both nRo60 and rRo60 were used to manufacture ELISA kits under
production conditions used for the newly available AI-Line ELISA series
(Dr. Fooke Laboratories). In study 1, 113 sera of different SARD were
tested to evaluate the correlation between rRo60 and nRo60. 328 sera
from patients suffering from SjS, SLE, SSc and myositis were tested in
study 2 with the new AI-Line Ro60 ELISA based on rRo60 and an
addressable laser based assay with nRo60 (ALBIA, FDA approved, INOVA
Diagnostics, Inc).
The antigen comparison of rRo60 and nRo60 in AI-Line ELISA showed good
correlation between rRo60 and nRo60 (Pearson´s r=0.98; p< 0.0001).
For the majority (~89%) of positive sera the signal intensities for the
rRo60 setup did not differ by more than 25% when compared to the nRo60
setup. The agreement of results between AI-Line rRo60 ELISA and ALBIA
ranged from 88 to 90% dependent on the cut-off of ALBIA.
We conclude that rRo60 is comparable to nRo60. Further, the new AI-Line
Ro60 ELISA based on the new rRo60 represents a reliable test with good
qualitative agreement to ALBIA with nRo60. | 17400 | Ro/SS-A (60 kDa; recombinant) | 0.1 mg | | 17401 | Ro/SS-A (60 kDa; recombinant) | 1.0 mg |
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North American Distributor |
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SurModics, Inc.
9924 West 74th Street
Eden Prairie, MN 55344
Tel.: 952-829-27709
Fax 952-829-2743
Toll Free (800) 755-7793
www.surmodicsIVD.Com
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