5'-nucleotidase activity in lymphocytes from patients affected by B-cell chronic lymphocytic leukemia.
OBJECTIVE
The activity of membrane-bound ecto-5'-nucleotidase and soluble e-Ns and c-N-II 5'-nucleotidases was evaluated on lymphocytes from patients affected by B-cell chronic lymphocytic leukemia (B-CLL). A statistically significative decrease in ecto-5'-nucleotidase, e-Ns, and c-N-II activities was observed in peripheral blood lymphocytes and in B and T populations from affected individuals.


METHODS
For the assay of ecto-5'-nucleotidase, e-Ns, and c-N-II activity we used a radioactive procedure coupled to HPLC. Since the ecto-5'-nucleotidase is identified as CD73 antigen, we performed immunofluorescence analysis using a specific monoclonal antibody. We analyzed ecto-5'-nucleotidase mRNA by RT-PCR to ascertain the possibility of an alteration in the transcription of its gene.


RESULTS
A decrease in ecto-5'-nucleotidase activity was correlated to reduction in ecto-5'-nucleotidase positive cells (CD73+) in leukemia patients. RT-PCR produced a fragment of the expected size and the specific mRNA was found expressed in both healthy subjects and leukemia patients.


CONCLUSIONS
The decrease in ecto-5'-nucleotidase activity in patients with B-CLL is not due to loss of transcription of the specific mRNA. The presence of point mutations, splicing alteration, or posttranslational modifications must be investigated. If a defect at DNA or RNA level will be detected, the molecular analysis will be considered for diagnosis of B-cell chronic lymphocytic leukemia.
Rosi
F
F
Institute of Biochemistry and Enzymology, University of Siena, Italy.
Tabucchi
A
A
Carlucci
F
F
Galieni
P
P
Lauria
F
F
Zanoni
L
L
Guerranti
R
R
Marinello
E
E
Pagani
R
R
D015720:5'-Nucleotidase / Q000097:blood* / Q000172:deficiency / Q000235:genetics; D000368:Aged; D015152:Blotting, Northern; D004789:Enzyme Activation; D005455:Fluorescent Antibody Technique; D006801:Humans; D007527:Isoenzymes / Q000097:blood / Q000172:deficiency; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000097:blood* / Q000201:enzymology*; D008214:Lymphocytes / Q000201:enzymology*; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis
D007527:Isoenzymes; D012333:RNA, Messenger; D015720:5'-Nucleotidase