Assessment of Serum Tryptase Activity Among Acute and Chronic Myeloid Leukemia Patients Visiting Hematology-Oncology Clinic at TikurAnbessa Specialized Hospital, and Comparison with Healthy Controls

Tryptase is a serine protease that is expressed in leukemic cells of chronic myeloid leukemia (CML) patients and in blasts of acute myeloid leukemia (AML) patients. Tryptase may be useful for diagnosis, assessment of severity of disease (leukemic cell burden), monitoring minimal residual disease and prognosis of AML and CML patients. The main objective of this study was to assess the serum levels of tryptase activity among CML and AML patients and to compare the serum levels of tryptase activity of acute and chronic myeloid leukemia patients with each other and with those of healthy controls. To meet this objective, a hospital-based comparative cross-sectional study was conducted among CML and AML patients from February 2016 up to December 2016. Serum samples were obtained from 24 AML, 60 CML and 35 healthy controls. Fluorogenic assays for serum tryptase activity using aminomethylcoumarin (AMC) peptide derivative were carried out. Statistical analysis was done by using SPSS version 20. Descriptive statistics, Paired Samples T-test, Wilcoxon Signed Rank test and Spearman’s rho test were used to investigate any correlation among different parameters. The minimum level of statistical significance was set at p-value <0.05. Accordingly, the mean and median serum levels of tryptase activity were significantly higher in patients with AML and CML than in the healthy controls (P-value < 0.05). CML patients in chronic phase (CP) and secondary AML patients had significantly higher mean and median serum levels of tryptase activity than CML patients in accelerated/blast phase (AP/BP) and de novo AML patients (p-value < 0.05). These elevated mean and median levels of serum tryptase activities were due to a subset of individuals with elevated serum tryptase levels (41.7 % of AML & 30 % of CML); the remaining leukemic individuals (58.3 % AML & 70 % of CML) had normal serum levels of tryptase activity. Finally, it was concluded that the serum tryptase level might be a useful diagnostic and prognostic marker in a subset of patients with CML and AML. However, further studies that incorporate other protocols such as tryptase immunoassay are warranted to exclude contaminant non-tryptase proteases from the serum samples