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Plasma thrombopoietin (TPO) levels and expression of TPO receptor on platelets in patients with myelodysplastic syndromes
Author(s) -
Hideto Tamura,
Kíyoyuki Ogata,
ShanShun Luo,
Kimihito Nakamura,
Norio Yokose,
Kazuo Dan,
Kaoru Tohyama,
Yataro Yoshida,
Hiroyuki Hamaguchi,
Hisashi Sakamaki,
Tomoaki Kuwaki,
Tomoyuki Tahara,
Takashi Kato,
Takeo Nomura
Publication year - 1998
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 - 10.1046/j.1365-2141.1998.01054.x
Subject(s) - thrombopoietin , medicine , megakaryocyte , platelet , endocrinology , myelodysplastic syndromes , thrombopoiesis , receptor , bone marrow , biology , haematopoiesis , stem cell , genetics
Data on endogenous thrombopoietin (TPO) levels and their regulation in myelodysplastic syndromes (MDS) are sparse. We examined the plasma TPO level of 85 MDS patients by a sensitive enzyme immunoassay and the platelet expression of TPO receptor (TPO‐R) protein, which metabolizes endogenous TPO, in 19 MDS patients with an equilibrium binding assay using 125 I‐TPO. The MDS patients had higher plasma TPO levels (7.0 ± 9.3 fmol/ml) than 52 normal subjects ( P < 0.0001). Refractory anaemia (RA) patients ( n = 39) had higher plasma TPO levels than patients ( n = 28) with RA with excess blasts (RAEB) or RAEB in transformation (RAEB‐t) ( P = 0.0002), irrespective of similar platelet counts in these groups. The plasma TPO level correlated inversely with the platelet count in RA patients ( P = 0.0027) but not in RAEB and RAEB‐t patients ( P = 0.7865). These data suggest that the physiological pathway for TPO production and metabolism is conserved, at least partially, in RA, but deranged in RAEB/RAEB‐t. The number of TPO‐R per platelet was significantly smaller in 19 MDS patients (17.5 ± 13.3) than in normals ( P = 0.0014), but similar between RA patients and patients with RAEB and RAEB‐t. Further, the bone marrow megakaryocyte count, determined in 31 MDS patients, was quite similar between RA patients and patients with RAEB or RAEB‐t. Thus, in addition to thrombocytopenia, a reduced platelet TPO‐R number may contribute to elevated plasma TPO levels in MDS, and a regulatory pathway for circulating TPO other than platelet TPO‐R and marrow megakaryocytes, such as blasts expressing TPO‐R, may operate in RAEB/RAEB‐t.