Serum thrombopoietin levels in patients with aplastic anaemia

Abstract

Endogenous serum thrombopoietin (TPO) levels were measured in 31 patients with aplastic anaemia (AA) using an enzyme immunoassay with a sensitivity of 20 pg/ ml. The median platelet count for all AA patients was 30 +/- 29 x 10(9)/l (range 5-102) compared with a median of 284 +/- 59 x 10(9)/l (range 148-538) for normal controls. Serum TPO levels were significantly elevated in all patients compared with normals (1706 +/- 1114.2, range 375-5000 v 78 +/- 54, range 16.5-312.9, P < 0.0001). There was no correlation between serum TPO levels and the degree of thrombocytopenia in AA patients, but TPO levels were significantly higher in patients who were platelet transfusion dependent than in patients who were transfusion independent (P < 0.01). There was a trend for higher TPO levels in patients with severe AA compared with non-severe AA patients. Clinical trials of TPO and a related truncated, pegylated molecule, megakaryocyte growth and development factor (PEG-rHuMGDF), are awaited to determine whether treatment with these drugs will result in increased platelet counts in patients with AA.

Thrombopoietic cytokines in relation to platelet recovery after bone marrow transplantation

“…Because not all patients had samples collected for platelet count daily and because not all specimens were sufficient for all three cytokine assays to be performed, the mean of all available platelet counts and cytokine assays is determined. From pretransplant to day +22 post-BMT, the median number of platelet counts assayed per day was 16 (range [10][11][12][13][14][15][16][17][18][19]; from day 23 to 42 the median number assayed per day was 11 (6)(7)(8)(9)(10)(11)(12). Similarly, for the blood cytokines, to day 22 the median number of daily samples was 15 (11)(12)(13)(14)(15)(16)(17)(18)(19) while beyond day 22 a median of 11 (6-13) specimens per day was assayed for cytokines.…”

“…9 Plasma TPO levels were assayed at Amgen (Thousand Oaks, CA, USA) using a polyclonal antibody-based ELISA with a range in plasma of 80 ± 5 pg/ml from subjects with platelet counts in the normal range. [6][7][8]17 Serial platelet counts were performed in the clinical hospital laboratory using automated cell counting equipment. …”

“…[1][2][3] Mpl ligand (sometimes known as thrombopoietin (TPO) 4 or megakaryocyte growth and differentiation factor (MGDF)), [5][6][7] interleukin-6 (IL-6), [8][9][10] IL-11, [11][12][13] IL-3 [14][15][16] and others have been identified as able to support megakaryocytopoiesis and platelet production. However, their in vivo interaction and contribution to platelet recovery after intensive myelosuppressive cancer therapy have Correspondence: Dr D Weisdorf, Box 480 University of Minnesota Hospital, 420 Delaware Street SE, Minneapolis, Minnesota 55455, USA Received 21 May 1999; accepted 18 November 1999 not been fully explored.…”

Changes in endogenous TPO levels during mobilization chemotherapy are predictive of CD34+ megakaryocyte progenitor yield and identify patients at risk of delayed platelet engraftment post-PBPC transplant

“…30 Briefly, the assay was constructed as a 'sandwich' in which a polyclonal rabbit anti-rHuML was used to capture TPO from the serum. The signal antibody used was a separate polyclonal rabbit anti-rhTPO linked to horseradish peroxidase.…”

“…24 It has therefore been proposed that serum TPO levels are reflective of total Mk mass. [24][25][26][27][28] With the recent development of sensitive ELISAs, [28][29][30] changes in endogenous TPO levels may be used as an indicator of the Mk reserve of patients undergoing PBPCT.…”