Adenosine Deaminase 1 as a Biomarker for Diagnosis and Monitoring of Patients with Acute Lymphoblastic Leukemia

BACKGROUND: Acute lymphoblastic leukemia (ALL) is known as the most prevalent pediatric malignancy all around the world. Identification of specific biomarker is necessary for early diagnosis and effective therapy. It is believed that Adenosine deaminase (ADA) as an enzyme involved in the purine salvage pathway increases in ALL patients. Herein, the quantity and pattern of ADA isoenzymes were surveyed among ALL patients in comparison to healthy subjects. METHODS: Serum and RBC samples of three different groups of ALL patients, including newly diagnosed cases without any drugs administration, subjects with the relapsed disease, patients in the remission stage after therapy, and the healthy subjects were enrolled in the study. Then, the activity and pattern of ADA1, ADA2 and ADA1+cp were determined using ADA kit and electrophoresis on SDS-PAGE, respectively. To confirm the presence of ADA enzyme, the fresh serums, extractions from erythrocytes, JM cell line as a human T lymphocyte line and J774 A.1 as mouse monocyte line were electrophoresed on 1.2% agarose gel and stained with the specific dye. RESULTS: The activities of ADA1 isoenzyme and total ADA in new cases and subjects with the relapsed disease were significantly higher than their activities in the patients in the remission stage and healthy controls (p<0.001). The unbounded ADA1 isoenzyme was found to exist in the erythrocyte, lymphocyte and monocyte. But in serum, all the ADA1 was bounded to the cp protein. CONCLUSIONS: ADA1 is the key isoenzyme elevating in ALL patients, therefore this isoenzyme could be a useful biomarker to diagnose ALL patients and monitor their therapies.