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Concanavalin A induces patching/capping of the platelet membrane glycoprotein IIb/IIIa complex
R M Kakaiya1, T L Kiraly, R G Cable
1American Red Cross Blood Services, Connecticut Region, Farmington 06032.
Thrombosis and Haemostasis
|April 8, 1988
Summary
Concanavalin A (Con A) induces capping of platelet membrane glycoprotein IIb/IIIa. This suggests glycoprotein IIb/IIIa redistribution is key to platelet attachment and spreading.
Area of Science:
- Hematology
- Cell Biology
- Biochemistry
Background:
- Platelet activation involves receptor-ligand interactions.
- Concanavalin A (Con A) is known to bind platelet glycoproteins.
- Previous studies observed Con A-induced receptor capping on platelets.
Purpose of the Study:
- To investigate the molecular mechanism of Con A-induced capping in human platelets.
- To determine if Con A capping involves the platelet membrane glycoprotein IIb/IIIa complex.
Main Methods:
- Human platelets were treated with unlabeled Con A.
- Platelets were stained with antibodies against glycoprotein IIb/IIIa and FITC-labeled secondary antibodies.
- Con A receptor capping was assessed using FITC-labeled anti-Con A antibodies.
- Inhibitory effects of methyl-alpha-D-mannopyranoside, cold temperature, and colchicine were evaluated.
Main Results:
- An average of 12-16% of platelets showed glycoprotein IIb/IIIa capping after Con A treatment.
- FITC-Con A induced capping in approximately 15% of platelets.
- Capping was significantly inhibited by methyl-alpha-D-mannopyranoside, cold, and colchicine pre-treatment.
Conclusions:
- Con A-induced capping in human platelets involves the patching and capping of the glycoprotein IIb/IIIa complex.
- Glycoprotein IIb/IIIa redistribution may play a critical role in platelet attachment and spreading.