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E Rubinstein, I Urso, C Boucheix and RC Carroll
Department of Medical Biology, University of Tennessee, Medical Center,
Knoxville 37920.
The effect on platelet activation of monoclonal antibodies directed against
common determinants of the HLA class I heavy chain molecule was studied.
Cross-linking W6/32, an anti-HLA class I of IgG2a subclass, led to platelet
activation. Two other antibodies of the same subclass did not have this
effect on platelets. The lack of activity of the F(ab')2 fragments suggests
that the activation signal is mediated by the platelet Fc receptor (Fc
gamma RII). Indeed, except for a higher sensitivity of W6/32 to aspirin and
apyrase, activations by cross- linking IV-3 (an anti-Fc gamma RII) and
W6/32 are similar at the level of InsP3 formation, calcium mobilization, pH
modifications, and activation of protein kinase C and myosin kinase. When
HLA class I molecules and Fc gamma RII are cross-linked together, platelet
activation occurs. This is not observed when a control IgG2a is substituted
for W6/32 or when CD9 and Fc receptor are cross-linked together. This
suggests that HLA class I molecules and Fc gamma RII synergize to activate
platelets.
This article has been cited by other articles:
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| Copyright © 1992 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
