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Soluble P‐selectin is present in normal circulation and its plasma level is elevated in patients with thrombotic thrombocytopenic purpura and haemolytic uraemic syndrome
Author(s) -
Katayama Masahiko,
Handa Makoto,
Araki Yohko,
Ambo Hironobu,
Kawai Yohko,
Watanabe Kiyoaki,
Ikeda Yasuo
Publication year - 1993
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1993.tb03149.x
Subject(s) - platelet , thrombotic thrombocytopenic purpura , p selectin , chemistry , medicine , endocrinology , von willebrand factor , glycoprotein , immunology , platelet activation , biochemistry
Summary. P‐selectin is an integral membrane glycoprotein stored in the secretory granules of platelets and endothelial cells. To determine whether soluble P‐selectin may be present in the circulation of healthy humans, we used a sandwich immunoassay to assess citrated plasma from 50 subjects. P‐selectin was present in concentrations ranging from 19 to 521 ng/ml (mean ± SD = 121 ± 84 ng/ml). The apparent molecular weight of P‐selectin immunoisolated from platelet‐poor plasma was similar to that of the detergent‐soluble form isolated from platelet membrane. Plasma levels of P‐selectin were unaffected by the following procedures: (1) drawing of blood in the presence of protease inhibitors; (2) stimulation of platelet‐rich plasma with aggregating agents; (3) ultracentrifugation at 1 g for 120 min at 4°C or filtration through a 0·22 μm membrane; or (4) preincubation of platelet‐poor plasma with immobilized anti‐platelet glycoprotein Ib monoclonal antibodies. It appeared that plasma P‐selectin did not result from the in vitro activation of platelets, nor was it derived from platelet microparticles. We also found that plasma P‐selectin levels were significantly elevated in patients with thrombotic thrombocytopenic purpura (12 patients, 332 ± 184 ng/ml, P<0.001) and haemolytic uraemic syndrome (17 patients, 297 ± 191 ng/ml, P < 0.0001), as compared to the normal levels. Thus, these data should facilitate the study of the pathophysiological significance of circulating P‐selectin.