| Autor: |
H I, Switalska, S, Niewiarowski, G P, Tuszynski, B, Rucinski, A H, Schmaier, T A, Morinelli, C S, Cierniewski |
| Rok vydání: |
1985 |
| Předmět: |
|
| Zdroj: |
The Journal of laboratory and clinical medicine. 106(6) |
| ISSN: |
0022-2143 |
| Popis: |
A method for radioimmunoassay of human thrombospondin was developed. Monospecific precipitating anti-human thrombospondin antibody was raised in rabbits after injection of thrombospondin purified by fibrinogen-agarose chromatography and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The linear portion of the thrombospondin radioimmunoassay standard curve was 0.5 to 20 ng/ml. Normal platelets and platelet-poor plasma contained 28,900 +/- 14,500 ng thrombospondin per 10(9) platelets and 60.6 +/- 10.7 ng/ml (mean +/- SD), respectively. Using radioimmunoassays for beta-thromboglobulin and thrombospondin antigens, we compared platelet location and secretion of these proteins. Both antigens shared similar distributions in platelet subcellular fractions with the largest amount localized to platelet alpha-granules. With thrombin (0.25 U/ml) as a platelet agonist, 62.4% and 19.5% of total beta-thromboglobulin and thrombospondin, respectively, were secreted from suspensions of washed human platelets. Because only 20% of the total platelet thrombospondin was secreted, further studies were initiated to determine whether the remaining thrombospondin became localized on the activated platelets membrane. 125I-Fab antithrombospondin specifically bound to activated platelets but not to unstimulated platelets. In contrast, 125I-Fab anti-beta-thromboglobulin did not bind to activated platelets. Plasma clearance of human beta-thromboglobulin (half-life fast 7.6 minutes, slow 56.6 minutes) and of human thrombospondin (half-life fast 29.9 minutes, slow 190 minutes) followed a biphasic exponential curve. In conclusion, both beta-thromboglobulin and thrombospondin are located in platelet alpha-granules, but they show a different pattern of secretion and expression on the platelet membrane and plasma clearance. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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