Serum Levels of Angiopoietin-2 and C-Reactive Protein in Chronic Myeloid Leukaemia Patients: Relation to Different Phases of the Disease

Serum levels of Angiopoietin-2 (Ang-2) and C-reactive protein (CRP) were measured in 50 patients with chronic myeloid leukemia (CML) (30 patients in chronic phase (group A) and 20 patients in advanced phase (group B)) and 15 healthy age and sex matched subjects as a control group, to investigate their relation to different phases of the disease. Serum levels of both Ang-2 and CRP were significantly higher (p<0.05) in patients group compared to controls, and in advanced stage compared to chronic phase. Furthermore a significant positive correlation was detected between Ang-2 and CRP in the whole patients group which could support the hypothesis that CRP might play a role in modulating angiogenesis. The present data suggest that both Ang-2 and CRP could play a role in the leukemic process. Understanding their roles may help in follow-up care and in designing new therapeutic strategies for CML. Furthermore, the role of CRP in modulating angiogenesis should not be underestimated.


INTRODUCTION
Chronic myeloid leukaemia (CML) is a clonal disease that results from an acquired genetic change in a pluripotential stem cell. (1) It is characterized by granulocytic leucocytosis, granulocytic immaturity, basophilia, anaemia, intense marrow granulocytic hyperplasia and splenomegaly. (2) It is a polyphasic disease which progresses from its chronic phase to an accelerated phase where the leukaemia is more difficult to control and additional chromosomal abnormalities appear, followed by a progressive increase in blast cells in blood and marrow termed the blastic phase or blast crisis. (3) Angiopoietin-2 (Ang-2) is a member of 516 Bull High Inst Public Health Vol.40 No. 3 [2010] the angiopoietin family; plays an important role in angiogenesis during the development and growth of human cancers. (4) The system involving Ang-2 and its receptor Tie-2, appears to play an important role not only in tumor angiogenesis, but also in the biology of haematological and non-haematological malignancies. (5) Ang-2 modulates angiogenesis in a cooperative manner with another important angiogenic factor, vascular endothelial growth factor (VEGF) (4) . In the presence of VEGF, Ang-2 collaborates at the front of invading vascular sprouts, serving as an initial angiogenic signal. (6) C-reactive protein (CRP) is a plasma protein, produced mainly by the liver (7) and by adipocytes. The aim of the present work was to study the serum level of Ang-2 and CRP in chronic myeloid leukemia patients, and their relation to different phases of the disease, also to investigate the angiogenic properties of CRP and to find out if there is any correlation between these two parameters. The diagnosis of CML was done by:

PATIENTS AND METHODS
 Standard morphology of peripheral blood and bone marrow films confirmed by PCR analysis of bcr/abl gene. (14)  Immunophenotyping (for blast cells) using a comprehensive panel of monoclonal antibodies (mAbs) against myeloid and lymphoid associated antigens as proposed by the European group for the characterization of leukaemia (EGCL) group. (15) was done to cases in blastic crisis.

Statistical methods:
Statistical analysis was done using SPSS program" version 17"(Statistical Package of social sciences, Chicago, USA)  (table 3).

Correlations between serum levels of
Ang-2 and CRP in patients:

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This finding is in accordance with the study of Quartarone et al. (5) who reported that in CML patients the serum level of Ang-2 was significantly higher than in controls.
Ang-2 modulates angiogenesis in a cooperative manner with the important angiogenic factor, vascular endothelial growth factor (VEGF). (5) Aguayo et al. (17) observed a significant increase in the number of blood vessels in CML. The increased vascularity was associated with a significant increase in VEGF.
In the present work, serum Ang-2 level was significantly higher in CML patients in advanced stage (group B) than in patients in chronic phase (group A). This finding coincides with the results of yerstovesk et al. (14) which /revealed that the expression of VEGF protein was more pronounced in the accelerated phase. They concluded that the expression of VEGF is dependant on the CML stage which could be of clinical importance in deciding the timing of therapy. In addition, Quartarone et al. (5) found that in patients with multiple  (18) who found significant associations between plasma VEGF and enlarged spleens. In contrast, yerstovesk et al. (14) reported that the level of VEGF expression correlated inversely with the degree of splenomegaly.
In the present study a statistically significant positive correlation was detected between serum Ang-2 level and blast percentages in the bone marrow. These findings are in accordance with the findings of Liu et al. (18) who reported significant association between plasma VEGF and blast percentage in chronic myeloid leukaemia.
As regard C-reactive protein, a statistically significant higher level was found in CML patients compared to controls, and in patients with advanced stage compared to those with chronic phase. These results are in accordance with the study of Akanni et al. (19) who showed that CRP level was significantly higher in the CML patients when compared to the controls. They attributed this to the rise in plasma concentration of interleukin-6 which is produced predominantly by the macrophages. (7) Also, Humlová et al. (20) reported In the present work a statistically