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N Kieffer, B Boizard, D Didry, JL Wautier and AT Nurden
We report the immunochemical characterization of a new platelet- specific
alloantigen detected using an IgG antibody isolated from the serum of a
patient with posttransfusion purpura (PTP). In indirect immunoprecipitation
experiments, the antibody, termed anti-Leka, predominantly precipitated
glycoprotein (GP) IIb from Triton X-100 lysates of normal human platelets.
In an immunoblot procedure, which involved the transfer of platelet
polypeptides separated by sodium dodecyl sulfate-polyacrylamide gel
electrophoresis to nitrocellulose membrane, anti-Leka bound exclusively to
GP IIb. Under identical conditions, four anti-PlA1 antibodies each reacted
with GP IIIa. No binding of anti-Leka IgG occurred to Leka (-) platelets or
to their separated polypeptides although GP IIb was normally detected by
Coomassie blue staining. After electrophoresis of reduced platelet
proteins, the Leka determinant was localized to the IIb alpha chain. Thus,
unlike the PlA1 antigen, the Leka determinant was not destroyed by
disulfide reduction. Analysis of platelets from a patient with Glanzmann's
thrombasthenia revealed little or no binding in the GP IIb position.
Anti-Leka permitted the identification of 76,000 and 60,000 dalton
fragments of GP IIb retained by the platelet following chymotrypsin
treatment. Our results further highlight the immunogenicity of the GP
IIb-IIIa complex. They also suggest that antibodies against GP IIb can
cause the thrombocytopenia observed in PTP and that anti-PlA1 antibodies do
not account exclusively for the pathophysiology of this immune disorder.
This article has been cited by other articles:
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| Copyright © 1984 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
