Platelet activation by polymorphonuclear leukocytes exposed to chemotactic agents

A. Del Maschio, V. Evangelista, G. Rajtar, Z. M. Chen, C. Cerletti, G. De Gaetano

Research output: Contribution to journalArticle

Abstract

Human platelets were loaded with aequorin, a Ca2+-sensitive photoprotein, and tested in the platelet-ionized calcium aggregometer for simultaneous recording of platelet aggregation and intraplatelet Ca2+ levels both in the presence and in the absence of autologous polymorphonuclear leukocytes. Cells were exposed to one of three chemotactic stimuli: platelet-activating factor (PAF), N-formyl-methionyl-leucyl-phenylalanine (FMLP), or leukotriene B4 (LTB4). Platelets alone aggregated and showed intracellular Ca2+ movement only when exposed to PAF. Amplification of both platelet aggregation and intraplatelet Ca2+ movement was induced by PAF in the presence of leukocytes. Aggregation and intraplatelet Ca2+ mobilization were also observed in the presence of leukocytes activated by either FMLP or LTB4. Both parameters increased with the concentration of the stimuli and/or the number of leukocytes. Platelet thromboxane B2 production was also significantly increased in the presence of leukocytes. Addition of platelets at different times after leukocyte activation resulted in progressively reduced cytoplasmic Ca2+ increase. Cell-free supernatants prepared from FMLP-stimulated leukocytes were able to induce platelet aggregation, thromboxane B2 generation, and Ca2+ mobilization, although at a reduced degree as compared with intact leukocyte addition. The activity of leukocyte supernatants was able at 37°C for up to 30 min and was suppressed by trypsin inhibitor. Our study indicates that stimulated leukocytes release a soluble enzymatic activity able to activate platelets; cell-to-cell interaction may also play a role in this phenomenon. Platelet-leukocyte interaction could have physiopathological relevance and constitutes a new model for studying old and new platelet inhibitory drugs.

Original languageEnglish
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume258
Issue number3 27-3
Publication statusPublished - 1990

Fingerprint

Platelet Activation
Neutrophils
Leukocytes
Blood Platelets
Platelet Activating Factor
Platelet Aggregation
methionyl-leucyl-phenylalanine
Thromboxane B2
Leukotriene B4
Luminescent Proteins
Aequorin
N-Formylmethionine Leucyl-Phenylalanine
Trypsin Inhibitors
Leukocyte Count
Cell Communication
Calcium

Keywords

  • blood cell interaction
  • cytoplasmic calcium ion movements
  • leukotriene B
  • N-formyl-methionyl-leucyl-phenylalanine
  • platelet-activating factor
  • thromboxane B

ASJC Scopus subject areas

  • Physiology

Cite this

Platelet activation by polymorphonuclear leukocytes exposed to chemotactic agents. / Del Maschio, A.; Evangelista, V.; Rajtar, G.; Chen, Z. M.; Cerletti, C.; De Gaetano, G.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 258, No. 3 27-3, 1990.

Research output: Contribution to journalArticle

@article{14bb4fd6331c4e3c9cfd19a0f3be2122,
title = "Platelet activation by polymorphonuclear leukocytes exposed to chemotactic agents",
abstract = "Human platelets were loaded with aequorin, a Ca2+-sensitive photoprotein, and tested in the platelet-ionized calcium aggregometer for simultaneous recording of platelet aggregation and intraplatelet Ca2+ levels both in the presence and in the absence of autologous polymorphonuclear leukocytes. Cells were exposed to one of three chemotactic stimuli: platelet-activating factor (PAF), N-formyl-methionyl-leucyl-phenylalanine (FMLP), or leukotriene B4 (LTB4). Platelets alone aggregated and showed intracellular Ca2+ movement only when exposed to PAF. Amplification of both platelet aggregation and intraplatelet Ca2+ movement was induced by PAF in the presence of leukocytes. Aggregation and intraplatelet Ca2+ mobilization were also observed in the presence of leukocytes activated by either FMLP or LTB4. Both parameters increased with the concentration of the stimuli and/or the number of leukocytes. Platelet thromboxane B2 production was also significantly increased in the presence of leukocytes. Addition of platelets at different times after leukocyte activation resulted in progressively reduced cytoplasmic Ca2+ increase. Cell-free supernatants prepared from FMLP-stimulated leukocytes were able to induce platelet aggregation, thromboxane B2 generation, and Ca2+ mobilization, although at a reduced degree as compared with intact leukocyte addition. The activity of leukocyte supernatants was able at 37°C for up to 30 min and was suppressed by trypsin inhibitor. Our study indicates that stimulated leukocytes release a soluble enzymatic activity able to activate platelets; cell-to-cell interaction may also play a role in this phenomenon. Platelet-leukocyte interaction could have physiopathological relevance and constitutes a new model for studying old and new platelet inhibitory drugs.",
keywords = "blood cell interaction, cytoplasmic calcium ion movements, leukotriene B, N-formyl-methionyl-leucyl-phenylalanine, platelet-activating factor, thromboxane B",
author = "{Del Maschio}, A. and V. Evangelista and G. Rajtar and Chen, {Z. M.} and C. Cerletti and {De Gaetano}, G.",
year = "1990",
language = "English",
volume = "258",
journal = "American Journal of Physiology",
issn = "0363-6119",
publisher = "American Physiological Society",
number = "3 27-3",

}

TY - JOUR

T1 - Platelet activation by polymorphonuclear leukocytes exposed to chemotactic agents

AU - Del Maschio, A.

AU - Evangelista, V.

AU - Rajtar, G.

AU - Chen, Z. M.

AU - Cerletti, C.

AU - De Gaetano, G.

PY - 1990

Y1 - 1990

N2 - Human platelets were loaded with aequorin, a Ca2+-sensitive photoprotein, and tested in the platelet-ionized calcium aggregometer for simultaneous recording of platelet aggregation and intraplatelet Ca2+ levels both in the presence and in the absence of autologous polymorphonuclear leukocytes. Cells were exposed to one of three chemotactic stimuli: platelet-activating factor (PAF), N-formyl-methionyl-leucyl-phenylalanine (FMLP), or leukotriene B4 (LTB4). Platelets alone aggregated and showed intracellular Ca2+ movement only when exposed to PAF. Amplification of both platelet aggregation and intraplatelet Ca2+ movement was induced by PAF in the presence of leukocytes. Aggregation and intraplatelet Ca2+ mobilization were also observed in the presence of leukocytes activated by either FMLP or LTB4. Both parameters increased with the concentration of the stimuli and/or the number of leukocytes. Platelet thromboxane B2 production was also significantly increased in the presence of leukocytes. Addition of platelets at different times after leukocyte activation resulted in progressively reduced cytoplasmic Ca2+ increase. Cell-free supernatants prepared from FMLP-stimulated leukocytes were able to induce platelet aggregation, thromboxane B2 generation, and Ca2+ mobilization, although at a reduced degree as compared with intact leukocyte addition. The activity of leukocyte supernatants was able at 37°C for up to 30 min and was suppressed by trypsin inhibitor. Our study indicates that stimulated leukocytes release a soluble enzymatic activity able to activate platelets; cell-to-cell interaction may also play a role in this phenomenon. Platelet-leukocyte interaction could have physiopathological relevance and constitutes a new model for studying old and new platelet inhibitory drugs.

AB - Human platelets were loaded with aequorin, a Ca2+-sensitive photoprotein, and tested in the platelet-ionized calcium aggregometer for simultaneous recording of platelet aggregation and intraplatelet Ca2+ levels both in the presence and in the absence of autologous polymorphonuclear leukocytes. Cells were exposed to one of three chemotactic stimuli: platelet-activating factor (PAF), N-formyl-methionyl-leucyl-phenylalanine (FMLP), or leukotriene B4 (LTB4). Platelets alone aggregated and showed intracellular Ca2+ movement only when exposed to PAF. Amplification of both platelet aggregation and intraplatelet Ca2+ movement was induced by PAF in the presence of leukocytes. Aggregation and intraplatelet Ca2+ mobilization were also observed in the presence of leukocytes activated by either FMLP or LTB4. Both parameters increased with the concentration of the stimuli and/or the number of leukocytes. Platelet thromboxane B2 production was also significantly increased in the presence of leukocytes. Addition of platelets at different times after leukocyte activation resulted in progressively reduced cytoplasmic Ca2+ increase. Cell-free supernatants prepared from FMLP-stimulated leukocytes were able to induce platelet aggregation, thromboxane B2 generation, and Ca2+ mobilization, although at a reduced degree as compared with intact leukocyte addition. The activity of leukocyte supernatants was able at 37°C for up to 30 min and was suppressed by trypsin inhibitor. Our study indicates that stimulated leukocytes release a soluble enzymatic activity able to activate platelets; cell-to-cell interaction may also play a role in this phenomenon. Platelet-leukocyte interaction could have physiopathological relevance and constitutes a new model for studying old and new platelet inhibitory drugs.

KW - blood cell interaction

KW - cytoplasmic calcium ion movements

KW - leukotriene B

KW - N-formyl-methionyl-leucyl-phenylalanine

KW - platelet-activating factor

KW - thromboxane B

UR - http://www.scopus.com/inward/record.url?scp=0025364026&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0025364026&partnerID=8YFLogxK

M3 - Article

C2 - 2156456

AN - SCOPUS:0025364026

VL - 258

JO - American Journal of Physiology

JF - American Journal of Physiology

SN - 0363-6119

IS - 3 27-3

ER -