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Human platelet activation by C3a and C3a des-arg.

Human platelet activation by C3a and C3a des-arg. C3a liberated from C3 by treatment with C3 convertase (or by trypsin) induced aggregation of gel-filtered human platelets and stimulated serotonin release. At concentrations of 10(-10) M to 8 X 10(-12) M, C3a induced aggregation when added alone to platelets. However, at lower concentrations (2 X 10(-12) M) C3a did not aggregate platelets directly but exhibited highly significant synergism (two-way analysis of variance P less than 0.0001) with ADP in mediating platelet aggregation and release of serotonin. Removal of the C-terminus arginine from C3a abolished anaphylotoxin activity but did not affect the platelet-stimulating activity of the peptide. C3a and C3a des-arg were equally reactive in mediating platelet aggregation and release of serotonin. Further C3a and C3a des-arg exhibited synergism with ADP of equal significance in both aggregation and the release reaction. The concentrations of C3a required for the platelet-stimulating activity involve relatively small number of molecules per platelet (4,000-10,000 for the synergistic reaction with ADP). These data suggest the possibility of a C3a (C3a des-arg) receptor on human platelets. This premise is strengthened by the demonstration ultrastructurally of C3a on the platelet membrane subsequent to C3a stimulation. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Experimental Medicine Rockefeller University Press

Human platelet activation by C3a and C3a des-arg.

The Journal of Experimental Medicine , Volume 158 (2): 603 – Aug 1, 1983

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References (35)

Publisher
Rockefeller University Press
Copyright
© 1983 Rockefeller University Press
ISSN
0022-1007
eISSN
1540-9538
DOI
10.1084/jem.158.2.603
Publisher site
See Article on Publisher Site

Abstract

C3a liberated from C3 by treatment with C3 convertase (or by trypsin) induced aggregation of gel-filtered human platelets and stimulated serotonin release. At concentrations of 10(-10) M to 8 X 10(-12) M, C3a induced aggregation when added alone to platelets. However, at lower concentrations (2 X 10(-12) M) C3a did not aggregate platelets directly but exhibited highly significant synergism (two-way analysis of variance P less than 0.0001) with ADP in mediating platelet aggregation and release of serotonin. Removal of the C-terminus arginine from C3a abolished anaphylotoxin activity but did not affect the platelet-stimulating activity of the peptide. C3a and C3a des-arg were equally reactive in mediating platelet aggregation and release of serotonin. Further C3a and C3a des-arg exhibited synergism with ADP of equal significance in both aggregation and the release reaction. The concentrations of C3a required for the platelet-stimulating activity involve relatively small number of molecules per platelet (4,000-10,000 for the synergistic reaction with ADP). These data suggest the possibility of a C3a (C3a des-arg) receptor on human platelets. This premise is strengthened by the demonstration ultrastructurally of C3a on the platelet membrane subsequent to C3a stimulation.

Journal

The Journal of Experimental MedicineRockefeller University Press

Published: Aug 1, 1983

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