In order to evaluate the use of the activity of serum neutral polyribonucleotide hydrolase as diagnostic and therapeutic markers for leukemia, the enzyme activity was determined using polycytidylate (poly C), polyuridylate (poly U), polyadenylate (poly A), polyguanylate (poly G) or RNA as substrate in serum of patients with acute lymphocytic and myelogenous leukemia (ALL and AML) before and after chemotherapeutic measures against leukemia. Neutral polyribonucleotide hydrolase and proteins in serum of patients with leukemia were isolated and fractionated by a DEAE-cellulose column chromatography and high performance liquid chromatography (HPLC) to find out whether or not the enzymes and proteins specific to the blood cancer were present in serum of leukemia.
1. Neutral polyribonucleotide hydrolase activity in serum exhibited the highest activity with poly C as substrate and the activity decerased in the order of the activity with poly U and RNA as substrate. No or little activity, if any, was observed with poly A or poly G as substrate.
2. Neutral polyribonucleotide hydrolase activity in serum was significantly increased when determined with poly C or poly U as substrate, but unchanged with RNA as substrate.
3. The positive rate of serum neutral polyribinucleotide hydrolase activity as a marker for leukemia was comparatively high when the activity was measured with poly C and poly U as substrate. The degree of increment in the enzyme activity and the positive rate exhibited the highest value with neutral poly C hydrolase for myelogenous leukemia.
4. In six out of nine cases of ALL studied, the activity of neutral poly C hydrolase in serum was decreased with duration of chemotherapeutic measures against leukemia and returned toward the normal level.
5. Analyses of serum neutral polyribonucleotide hydrolase and proteins with a DEAE-
cellulose column chromatography and HPLC revealed that enzymes were present
in multiform in serum of ALL and AML, and that a part of the normal enzymes
and proteins disappeared and enzymes and proteins specific to the blood cancer
were found in leukemic serum.
These results indicated that the activity of neutral poly C hydrolase was significantly increased in serum of leukemia and that the serum enzyme could be used as diagnostic and therapeutic markers for ALL and AML. Also suggested were presence of neutral polyribonucleotide hydrolase and proteins specific to ALL and AML in the leukemic serum.
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