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Platelet‐associated immunoglobulins G, A and M are secreted during platelet activation: normal levels but defective secretion in grey platelet syndrome
Author(s) -
Pfueller Sharron L.,
David Rosemary
Publication year - 1988
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.1365-2141.1988.tb06195.x
Subject(s) - platelet , albumin , chemistry , thrombin , medicine , endocrinology , platelet activation , secretion , antibody , immunology , biochemistry , biology
Summary Platelet‐associated (PA) IgG is known to be released from normal human platelets when they are stimulated by aggregating agents. We have studied whether PA‐IgA and PA‐IgM are also secreted during platelet activation or during blood collection and processing and whether their levels are related to those in serum. Processing of platelets from normal donors in the presence of secretion inhibitors prostaglandin E 1 (PGE 1 ) and theophylline increased levels of both surface and total PA‐immunoglobulins (Ig) in intact and lysed platelets respectively, with increases being significant for surface PA‐IgA and PA‐IgM and total PA‐IgM. About 50% of total PA‐IgM, 40% PA‐IgA and 20% PA‐IgG was detectable on intact platelets. All three PA‐Ig and PA‐albumin were secreted in response to thrombin and this release was inhibited by PGE 1 . The platelet: serum ratio of each Ig and albumin were similar. In grey platelets deficient in α‐granules, PA‐Ig and PA‐albumin levels were raised per platelet but when increased platelet size was taken into account PA‐Ig were normal and PA‐albumin just below normal. Although thrombin caused release of most of the small amounts of β‐thromboglobulin present, PA‐Ig and PA‐albumin were not released. This suggests that PA‐Ig and albumin from plasma may enter a pool of secretory proteins in normal platelets, but in grey platelets they remain in some other site.