Intralymphocytic Adenosine Deaminase (ADA) and Purine Nucleoside Phosphorylase (PNPase) Activity in Chronic Lymphocytic Leukemia (CLL) : Effect of Thymostimulin

ADA (E.C.3.5.4.4.) and PNPase (E.C.2.4.2.1.) are enzymes which have been extensively studied by imnunologists ever since it was noted that a deficiency of either one of these enzymes could be associated with severe congenital immunodeficiency. Though the catalytic actions of these enzymes are sequential, the absence or the alteration of one of the two enzymes causes different types of congenital immunodeficiencies. ADA insufficiency causes a severe combined immunodeficiency while PNPase insufficiency alters delayed immunity (1,2). JVbreover it has been demonstrated that these enzymes are involved in lymphocytic ontogeny both in animals (3) and in man (4).