V. Thibert et al., INCREASED PLATELET CD36 CONSTITUTES A COMMON MARKER IN MYELOPROLIFERATIVE DISORDERS, British Journal of Haematology, 91(3), 1995, pp. 618-624
The distribution of the major platelet membrane glycoproteins (GP), Ib
, IX, IIb-IIIa and TV (or CD36), which play important roles as recepto
rs for adhesive molecules in haemostasis and thrombosis, was studied i
n 34 patients with myeloproliferative disorders (MPD): 13 had essentia
l thrombocythaemia (ET), 12 had polycythaemia vera (PV) and nine had c
hronic myelogenous leukaemia (CML). Only occasionally were modificatio
ns of the numbers of GPIb or GPIIb-IIIa measured using the binding of
specific radiolabelled antibodies to platelets. In contrast, 2-3-fold
increases of the total CD36 content and the surface CD36 expression we
re measured in almost all patients studied, using a radioimmunoassay a
nd the direct binding of the radiolabelled antibody, FA6-152, to the p
latelet surface, respectively. These results indicate that the abnorma
lity affected both the external and internal CD36 pools. Therefore pla
telet CD36 may be a useful tool for the diagnosis and the follow-up of
MPD patients. Surface CD36 has been proposed as a platelet receptor f
or thrombospondin, an adhesive glycoprotein that is released from plat
elets upon activation and promotes aggregate formation. Despite a 2-fo
ld increase of CD36 molecules, resting and thrombin-activated platelet
s from ET patients expressed the same amount of thrombospondin as norm
al platelets, suggesting that there is not a direct correlation betwee
n the CD36 expression and thrombospondin binding either spontaneously
or after activation.