[Characteristics of human platelet fibrinogen receptors regulated by anti-CD9 monoclonal antibodies].
OBJECTIVE
To investigate the regulatory effect of two anti-CD9 monoclonal antibodies (McAbs), HI117 and SJ9A4, on human platelet fibrinogen receptors, and explore their potential mechanisms.


METHODS
By using 125I-labeled human fibrinogen (Fg), the Fg specifically bound to human platelets induced by HI117 and SJ9A4 was measured, and the changes of anti-CD9 McAbs-exposed Fg receptor in the absence of Fg were also observed.


RESULTS
HI117 (10 micrograms/ml) and SJ9A4 (20 micrograms/ml) induced markedly the specific binding of Fg to human platelets, suggesting that the two McAbs evoked obvious exposure of Fg receptors. But in the absence of Fg, the McAbs-exposed Fg receptors gradually lost their capacity to bind Fg and closed. Further study indicated that HI117 and SJ9A4-induced Fg binding was reduced by pretreatment of platelets with sphingosine, aspirin, apyrase, and/or PGI2.


CONCLUSIONS
The anti-CD9 McAbs, HI117 and SJ9A4, can reversibly expose platelet Fg receptors, probably via three signaling pathways, i.e. thromboxane, secreted ADP and cAMP, protein kinase C (PKC) activation presumably being the common passage for the signaling.
Wu
H
H
Institute of Hematology, CAMS and PUMC, Tianjin 300020.
Li
J
J
Peng
L
L
D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D015703:Antigens, CD / Q000276:immunology*; D001792:Blood Platelets / Q000378:metabolism*; D006801:Humans; D008562:Membrane Glycoproteins; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000096:biosynthesis*; D060245:Tetraspanin 29
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; C554869:CD9 protein, human; D008562:Membrane Glycoproteins; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D060245:Tetraspanin 29