Ganglioside Content of Human Platelets – Differences in Resting and Activated Platelets

Abstract

SummaryGangliosides may play functional roles in platelet physiology, therefore this study has been designed to evaluate whether changes in ganglioside composition may occur as a consequence of platelet activation. The results obtained indicate that lactosylceramide and GM3 are the major glycosphingolipids of human platelets. The lipid-bound sialic acid (LBS A) content was 1.27 ± 0.04µεg/mg of protein. Resting platelets did not express GD3; GD3 was synthesized upon platelet activation (24 ± 8 ng/mg of protein). The stimulation of platelets with adenosine diphosphate showed the appearance of GD3 even in the absence of degranulation. Finally, incorporation of pyrene-labeled GM3 into platelet membranes, followed by stimulation with adenosine diphosphate, resulted in the appearance of a fluorescent band comigrating with GD3. The present studies indicate that sialyltransferase activation may occur as an early event following platelet stimulation, leading to GD3 synthesis mainly from the GM3 pool.

Alterations in Bcl‐2/Bax protein levels in platelets form part of an ionomycin‐induced process that resembles apoptosis

“…Our data indicate an increased level of Bcl-2 and Bax after ionomycin-induced activation of platelets. Others have demonstrated synthesis of GM3 ganglioside (Ferroni et al, 1997), HLA class I molecules (Santoso et al, 1993) and other platelet proteins (Newman et al, 1988). However, increased protein synthesis will not necessarily be a general response to the activation of platelets.…”

Acute inflammatory sensorimotor polyradiculoneuropathy associated with immune thrombocytopenic purpura

“…There have been no reports that showed their expression in the nervous tissue so far. Conversely, the ganglioside constituents of platelets are known to be completely different from those of the nervous tissue [11]. Thus, it is not easy to show the presence of a common antigen that would explain the association of AIP and ITP, though possibility remains that they share a common target epitope.…”

Human platelets express gangliosides with LKEactivity and ABH blood group activity

“… 21–23 Platelets also express type 2 chain gangliosides with sialyl‐ iI (siI) and sialyl‐Le x (sLe x ) activity 24 . Biologically, platelet gangliosides are hypothesized to play a role in megakaryocyte differentiation, 25,26 platelet activation, 21,22 serotonin metabolism, 27 platelet adhesion, 4,24 and platelet storage lesion 23 . Auto antibodies to platelet gangliosides may also play a role in autoimmune thrombocytopenia 28 …”