Platelets release their lysosomal content in vivo in humans upon activation

Silvia Ciferri, Carla Emiliani, Giuseppe Guglielmini, Antonio Orlacchio, Giuseppe G. Nenci, Paolo Gresele

Research output: Contribution to journalArticlepeer-review


Platelets contain, besides α- and δ-granules, lysosomes which store glycohydrolases able to degrade glycoproteins, glycolipids and glycosaminoglycans. While several studies have shown that α- and δ-granule secretion takes place 'in vivo' in humans upon platelet activation, no data are available on the 'in vivo' release of lysosomes. We have studied the release of platelet lysosomal contents 'in vivo' in healthy volunteers at a localized site of platelet activation by measuring markers of lysosomal secretion in the blood oozing from a skin wound inflicted for the measurement of the bleeding-time. The levels of β-N-acetylhexosaminidase (Hex) were 13.1 ± 0.85 mU/ml in bleeding-time blood and 10.2 ± 0.66 mU/ml in plasma (p <0.001). Hex in serum was 16.4 ± 0.72 mU/ml. The levels of β-galactosidase were also higher in bleeding-time blood than in plasma (0.85 ± 0.07 mU/ml vs 0.4 ± 0.05 mU/ml, p <0.001). In bleeding-time blood collected at one minute intervals, Hex rose progressively consistent with ongoing platelet activation and flow-cytometry showed a progressive increase of the expression of LIMP and LAMP-2, two lysosomal associated proteins. In conclusion, our data demonstrate that platelet lysosomal glycohydrolases are released 'in vivo' in humans upon platelet activation.

Original languageEnglish
Pages (from-to)157-164
Number of pages8
JournalThrombosis and Haemostasis
Issue number1
Publication statusPublished - 2000


  • Bleeding time
  • Flow cytometry
  • LIMP and LAMP2
  • Platelet secretion
  • Platelet vessel wall interaction

ASJC Scopus subject areas

  • Hematology


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