[Serum adenosine deaminase and its isozyme activity in leukemia and MDS].

We studied the activity of serum adenosine deaminase (ADA) and its isozyme in 36 leukemic patients (16 ANLL, 11 ALL, and 9 CML) and 8 MDS. Isozyme was measured by erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) inhibitory assay. This assay was simple and reliable. The appearance rate of abnormally high ADA value were 81.24% for ANLL, 100% for ALL, 77.8% for CML and 37.5% for MDS. The ADA level became high when MDS turned into overt leukemia. In isozyme pattern, there was a clear difference between ANLL and ALL. The isozyme I/II ratio was significantly higher (p less than 0.001) in ALL than ANLL. Lymphoblastic crisis of CML also had a high isozyme I/II ratio. There was a correlation between isozyme I and absolute number of peripheral blasts in ALL (r = 0.768). When observed time sequentially, ADA and isozyme changed correlatively with the number of blasts counts. Serum ADA and its isozyme are useful parameters both for leukemic diagnosis and treatment.