Pyrimidine 5′‐nucleotidase activity in normal and deficient human lymphoblastoid cells

Abstract

Two distinct pyrimidine 5'-nucleotidases (UMPH-1 and UMPH-2) have previously been detected in human erythrocytes; UMPH-1 is deficient in a haemolytic anaemia, while UMPH-2 is unaffected. Only the erythrocyte shows pathological effects in this disorder. Here we have studied lymphoblastoid cell lines from control and UMPH-1 deficient patients to determine whether UMPH-1 can be detected in lymphoblastoid cells and whether the deficiency of UMPH-1 results in any measurable metabolic effects. Both UMPH-1 and a UMPH-2-like activity were found to be present in control lymphoblastoid cells. UMPH-1 was undetectable in the patients' cells; minor but significant changes were found in the pyrimidine nucleotide and nucleoside pools in the cells.

Pyrimidine 5’Nucleotidase I and II Activities in Acute Leukaemias

“…This enzyme catalysis the dephosphorylation of 5' nucleotides and exists on the membranes of human peripheral-blood lymphoid cells. In some studies enzyme activity was measured in erythrocytes, T and B-lymphocytes, mononuclear and plasma cells (6,8,14). In our study 5' NT activity was determined in mononuclear cells.…”

“…In our study 5' NT activity was determined in mononuclear cells. As the analysis of enzymatic methods are different from previous studies we were unable to discuss our results with them (2,6). We preferred to use HPLC, as the method is 50-fold more sensitive than that based on calorimetric measurements and furthermore avoids the use of radioactive materials (2).…”

“…In addition to traditional haemotological methods as morphology and cytochemistry, highly specific techniques are required nowadays for the identification and sophisticated characterization of malignant and normal haematological cells. There have been many exciting developments in the clinical utility of biochemical enzyme markers for both diagnostic and therapeutic purposes in acute leukaemia (4,5,6,8,14).…”

Pyrimidine 5′ Nucleotidase Deficiency

“…Most cells contain a number of different nucleotidases able to hydolyse pyrimidine monophosphates, which limits the effects of P5′N‐1 deficiency largely to the red cell. Nevertheless, it has been shown that in nucleated cells, P5′N‐1 deficiency results in abnormal pyrimidine nucleotide metabolism (Hopkinson et al , 1990).…”

“…For example, uridine monophosphate can be used as a substrate and the rate of uridine released by the action of P5′N‐1 quantified by HPLC (Simmonds et al , 1991). Other diagnostic techniques include electrophoretic analysis of P5′N isozymes, demonstrating an absence of functional P5′N‐1 protein (Hopkinson et al , 1990), and nuclear magnetic resonance spectroscopy of P5′N‐1‐deficient red cells, which shows a diagnostic spectrum due to the accumulation of cytidine diphosphate (CDP)‐choline, pyrimidine nucleotides, CDP‐ethanolamine and uridine diphosphate (UDP)‐glucose (Vives‐Corrons, 2000).…”