Abstract | BACKGROUND:
Glycoprotein (GP)VI deficiency is a rare platelet disorder with a mild bleeding tendency. However, its pathophysiology remains unclear. OBJECTIVES: METHODS AND RESULTS: A 12-year-old Japanese girl (case 1) with moderate thrombocytopenia and mild bleeding showed selectively impaired collagen-induced platelet aggregation. Flow cytometric analysis indicated that the patient had a defect in the expression of GPVI-FcRgamma. An eluate of her platelet-associated IgG contained anti-alpha(IIb)beta3 autoantibodies. Moreover, using GPVI-FcRgamma-transfected cells, we unexpectedly identified anti-GPVI antibodies against the soluble ectodomain of GPVI in the eluate, despite the patient's GPVI deficiency. In contrast, anti-GPVI antibodies were not detectable in her plasma. In another case of GPVI deficiency (case 2) without detectable plasma anti-GPVI antibodies, we again detected platelet-associated anti-GPVI antibodies. In a 2-year follow-up of case 1, the platelet count increased to within the normal range and the bleeding tendency improved. Interestingly, GPVI was again expressed on her platelets, in association with a decrease in the relative amount of anti-GPVI antibodies. CONCLUSIONS: This is the first demonstration of platelet-associated anti-GPVI antibodies in GPVI-deficient subjects, in one case with spontaneous restoration of GPVI expression. These results strongly suggest an autoimmune mechanism in GPVI deficiency.
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Authors | M Akiyama, H Kashiwagi, K Todo, M Moroi, M C Berndt, H Kojima, Y Kanakura, Y Tomiyama |
Journal | Journal of thrombosis and haemostasis : JTH
(J Thromb Haemost)
Vol. 7
Issue 8
Pg. 1373-83
(Aug 2009)
ISSN: 1538-7836 [Electronic] England |
PMID | 19522742
(Publication Type: Case Reports, Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Autoantibodies
- Epitopes
- Platelet Membrane Glycoproteins
- platelet membrane glycoprotein VI
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Topics |
- Adult
- Autoantibodies
(analysis)
- Blood Platelets
(immunology)
- Child
- Epitopes
- Female
- Humans
- Platelet Membrane Glycoproteins
(biosynthesis, deficiency, immunology)
- Purpura, Thrombocytopenic, Idiopathic
(immunology)
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