Enzymatic differences between chronic lymphocytic leukemia and prolymphocytic leukemia.

Area of Science:

• Hematology
• Enzymology
• Oncology

Background:

• Chronic lymphocytic leukemia (CLL) and B-cell prolymphocytic leukemia (PLL) are related lymphoid neoplasms.
• Distinguishing between CLL and PLL is crucial due to differing clinical behaviors and treatment strategies.
• Cytomorphologic and clinical features can overlap, necessitating additional diagnostic markers.

Purpose of the Study:

• To investigate the utility of adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) enzyme activities in differentiating CLL from PLL.
• To explore PNP activity as a potential enzymatic marker for prolymphocytoid transformation of CLL.

Main Methods:

• Peripheral blood leukemic cells from patients with CLL, PLL, and CLL with prolymphocytoid transformation were analyzed.
• Adenosine deaminase and purine nucleoside phosphorylase activities were measured using a linked-enzyme spectrophotometric assay.
• Discriminant analysis was employed to differentiate between the patient groups based on enzyme activities.

Main Results:

• Purine nucleoside phosphorylase (PNP) activity significantly differentiated between CLL and PLL (F1,9; p < 0.001).
• PNP activity was markedly elevated in leukemic cells with prolymphocytic morphology (mean = 58.6 nM/min/mg protein) compared to lymphocytic morphology (mean = 25.6 nM/min/mg protein).
• One CLL patient was classified into the PLL group based on elevated PNP activity.

Conclusions:

• Purine nucleoside phosphorylase activity in leukemic cells serves as a valuable tool for distinguishing prolymphocytic leukemia from chronic lymphocytic leukemia.
• Elevated PNP activity may function as an enzymatic marker for the early detection of prolymphocytoid transformation in chronic lymphocytic leukemia.