Articles |
From the Laboratory of Vascular Biology and Human Immunology, Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.
Correspondence to Aldo Del Maschio, Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157 Milano, Italy. E-mail delmaschio{at}irfmn.mnegri.it
Abstract We report here that platelets adhere to cultured
endothelial cells (EC) on exposure to the integrin ß1
activating monoclonal antibody (mAb) BV7. The effect of BV7 is exerted
mostly on platelets rather than EC. BV7 does not induce
platelet aggregation or 5-hydroxytyptamine (5-HT) release and does
not increase platelet adhesion to matrix proteins. Another
activating ß1 mAb, Lia1/2, triggers an effect similar to BV7.
Blocking antibodies to
2 and ß1, but not to other integrin chains,
are able to inhibit BV7-mediated adhesion. Moreover, the effect of BV7
requires active cellular metabolism and is not inhibited by
platelet treatment with aspirin, by the PAF receptor
antagonist BN50730, the phosphokinase C
inhibitor staurosporin, or by the cAMP or cGMP enhancers
prostaglandin E1 and sodium nitroprusside, respectively.
Finally, BV7-mediated adhesion was enhanced by the
endoperoxide analogue U46619. These data describe a
novel mechanism of platelet adhesion to endothelial
cells. This adhesion pathway appears to be mediated by
2ß1-integrin on platelets and a still-undefined
endothelial counter receptor.
Key Words: platelets endothelial cells integrins adhesion
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