53
OCTOBER 16-18, 2011 • PORTLAND, OR
P17
Detection of autoantibodies against platelet
glycoproteins in patients with ITP by fow
cytometry
Yang He, Mingqing Zhu
The First Affliated Hospital of Soochow University,
Jiangsu Institute of Hematology,, Suzhou, China
Objective:
Autoantibodies against platelet
glycoproteins (GPs) exist in patients with idiopathic
thrombocytopenic purpura (ITP), contributing to
the disease mechanism. The aim of this study
is to establish a fow cytometric assay to detect
autoantibodies against platelets.
Methods:
Polystyrene beads were coated with monoclonal
antibodies SZ2, SZ22, SZ21 and 7E3 against
platelet GPs Ib, IIb, IIIa and IIb/IIIa, respectively, and
incubated with platelet lysate. Captured platelet GP/
antibody complexes were detected by FITC-labeled
anti-human Ig antibodies by fow cytometry. The
mean fuorescence intensity (MFI) in samples from
85 patients with ITP, 17 patients with non-ITP (NITP)
and 50 healthy controls was measured. The sensitivity
and specifcity of these antibodies for the diagnosis
of ITP were analyzed with the ROC curve, and
compared with those of the ELISA-based monoclonal
antibody immobilization of platelet antigen assay
(MAIPA).
Results:
The MFI of SZ2 in ITP group was
signifcantly higher than that in NITP and healthy
groups [1.49 (0.88-16.24)
vs
. 1.12 (1.0-1.33) and
1.01 (0.83-1.37),
p
<0.01]. Similarly, the MFI values
of SZ22, SZ21 and 7E3 were all higher in ITP group
than those in NITP and healthy groups [SZ22: 1.55
(0.84-11.30)
vs
. 1.13 (1.0-1.29) and 0.98 (0.85-1.24),
p
<0.01; SZ21: 1.50 (0.87-11.04)
vs
. 1.13 (0.97-1.32)
and 1.01 (0.85-1.48),
p
<0.01; and 7E3: 1.51(0.84-
9.81)
vs
. 1.05 (0.86-1.13) and 1.03 (0.74-1.28),
p
<0.01]. In ROC analysis, the area under the curve
was 0.86, 0.9, 0.87 and 0.84, and the sensitivity was
58.8, 52.9, 52.9 and 51.8%, respectively, for SZ2,
SZ22, SZ21 and 7E3. When all 4 antibodies were
used, the sensitivity for the diagnosis of ITP was
increased to 74.1%, signifcantly higher than that of
MAIPA (50.6%, χ
2
=6.78,
p
<0.05).
Conclusions:
Flow
cytometric assays with multiple antibodies detected
platelet-associate autoantibodies in patients with ITP
and increase the diagnostic sensitivity.
Key words
Flow cytometric assay, Autoantibody, Glycoprotein
POSTER ABSTRACTS