PROGNOSTIC-SIGNIFICANCE OF ADENOSINE-DEAMINASE IN CHILDREN WITH MALIGNANCIES

In 33 children, 23 with acute lymphoblastic leukemia (ALL) and 10 with solid tumors, the phenotype of the enzyme adenosine deaminase (ADA) w as detected in the erythrocytes by electrophoresis in cellulose acetat e. In all children the ADA enzyme activity was also determined in the plasma by spectrophotometry at the onset of the disease, during remiss ion, at the end of the therapy, and during relapse. The phenotype in a ll children was ADA1-1. There was a difference in enzyme activity betw een the mean values of children with ALL and those with solid tumors. There were also differences among tile subtypes of ALL and also among the stages of ALL and the stages of solid tumors. In 23 children with ALL the mean value (MV) and the corresponding standard error (SEM) of enzyme activity at the onset of the disease were MV +/- SEM = 60.2 +/- 6.2 IU/L. This was higher than that of the control group (control gro up: MV +/- SEM = 27.8 +/- 3.3 IU/L). During remission the enzyme activ ity was lower than that of the control group (MV +/- SEM = 19.6 +/- 1. 7 IU/L); at the end of the therapy it was MV +/- SEM = 24.0 +/- 1.3 IU /L, which is close to that of the control group; and during relapse it was much higher compared with the control group (MV +/- SEM = 73.1 +/ - 4.6 IU/L). These values are discussed in connection to the leukaemic subtypes. In 10 children with solid tumors the mean value of enzyme a ctivity at the onset of the disease was MV +/- SEM = 48.8 +/- 2.4 IU/L . During therapy it was MV +/- SEM = 32.4 +/- 1.9 IU/L and at tile end of therapy MV +/- SEM = 22.1 +/- 2.5 IU/L. The aim of this work is to study the qualitative isoenzyme abnormalities to better understand th e biological nature of the malignancies, to distinguish main groups an d subsets of ALL and solid tumors on an enzymatic basis, and to identi fy possible sensitive key enzymes as targets for chemotherapy.