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Title: Deoxyguanosine triphosphate as a possible toxic metabolite in the immunodeficiency associated with purine nucleoside phosphorylase deficiency. Author: Cohen A, Gudas LJ, Ammann AJ, Staal GE, Martin DW. Journal: J Clin Invest; 1978 May; 61(5):1405-9. PubMed ID: 96138. Abstract: Purine nucleoside phosphorylase (PNP) deficiency is associated with a severe defect in thymus-derived (T)-lymphocyte function combined with normal bone marrow-derived (B)-lymphocyte function. To investigate the role of this enzyme deficiency in the resulting immune dysfunction, we measured the levels of ribonucleoside and deoxyribonucleoside triphosphates in erythrocytes from two unrelated PNP-deficient, T-lymphocyte-deficient patients. Both PNP-deficient patients have abnormally high levels of deoxyguanosine triphosphate (deoxy-GTP) in their erythrocytes (5 and 8 nmol/ml packed erythrocytes). In contrast, normal controls and adenosine deaminase-deficient, immunodeficient patients do not have detectable amounts of deoxyGTP (<0.5 nmol/ml packed erythrocytes). We propose that deoxyguanosine, a substrate of PNP, is the potentially lymphotoxic metabolite in PNP deficiency. The mechanism of toxicity involves phosphorylation of deoxyguanosine to deoxyGTP, which acts as a potent inhibitor of mammalian ribonucleotide reductase.[Abstract] [Full Text] [Related] [New Search]