| Autor: |
Okita, Janice Rice, Frojmovic, Mony M., Kristopeit, Susan, Wong, Truman, Kunicki, Thomas J. |
| Zdroj: |
Blood; August 1989, Vol. 74 Issue: 2 p715-721, 7p |
| Abstrakt: |
Platelets from patients with Montreal platelet syndrome (MPS) consistently display a defect in the mechanisms that regulate platelet size during shape change and undergo spontaneous aggregation and stir-induced microaggregate formation. We now provide data that the surface glycoprotein composition of MPS platelets is indistinguishable from that of normal platelets. However, a defect in calcium-activated neutral proteinase (calpain) was detected in MPS platelets. The specific activity of calpain in the cytosolic fraction of platelets from four MPS patients was found to be only 30% of that in platelets from normal control donors (n = 18, P≪ .001). Additionally, platelets from MPS patients (n = 3) contained only 50% (P≪ .001) of the calpain I catalytic subunit antigen found in platelets from normal control donors (n = 9). Platelets from the asymptomatic father/grandfather of the MPS patients had normal amounts of both total calpain proteolytic activity and calpain I catalytic subunit antigen. This represents the first report of a defect in calpain in human cells. The abnormally low calpain activity in MPS platelets may account for the platelet defects characteristic of this disorder. © 1989 by Grune & Stratton, Inc. |
| Databáze: |
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