Charles A. Koller

Adenosine deaminase deficiency with normal immune function. An acidic enzyme mutation.

In most instances, marked deficiency of the purine catabolic enzyme adenosine deaminase results in lymphopenia and severe combined immunodeficiency disease. Over a 2-yr period, we studied a white male child with markedly deficient erythrocyte and lymphocyte adenosine deaminase activity and normal immune function. We have documented that (a) adenosine deaminase activity and immunoreactive protein are undetectable in erythrocytes, 0.9% of normal in lymphocytes, 4% in cultured lymphoblasts, and 14% in skin fibroblasts; (b) plasma adenosine and deoxyadenosine levels are undetectable and deoxy ATP levels are only slightly elevated in lymphocytes and in erythrocytes; (c) no defect in deoxyadenosine metabolism is present in the probands cultured lymphoblasts; (d) lymphoblast adenosine deaminase has normal enzyme kinetics, absolute specific activity, S20,w, pH optimum, and heat stability; and (e) the probands adenosine deaminase exhibits a normal apparent subunit molecular weight but an abnormal isoelectric pH. In contrast to the three other adenosine deaminase-deficient healthy subjects who have been described, the proband is unique in demonstrating an acidic, heat-stable protein mutation of the enzyme that is associated with less than 1% lymphocyte adenosine deaminase activity. Residual adenosine deaminase activity in tissues other than lymphocytes may suffice to metabolize the otherwise lymphotoxic enzyme substrate(s) and account for the preservation of normal immune function.

An assay of deoxyadenosine and adenosine in human plasma by HPLC

Abstract We have developed a method for the simultaneous measurement of deoxyadenosine and adenosine in human plasma. A barium hydroxidezinc sulfate extraction procedure circumvented acid precipitation and preserved the deoxyadenosine. Deoxyadenosine and adenosine were separated using reverse-phase high-pressure liquid chromatography and their identities were confirmed by the enzymatic peak shift technique. A radioactive internal standard was used to measure extraction efficiency and to prove completeness of enzyme treatment for the peak shift technique. This assay is sensitive to 100 n m of either nucleoside in plasma and can be completed within 1 hr. This technique can be used to quantitate plasma deoxyadenosine and adenosine in patients with congenital adenosine deaminase deficiency or in patients being treated with ADA inhibitors.

Bordetella bronchiseptica pneumonia in a patient with chronic lymphocytic leukemia

This case report describes two episodes of pneumonia caused by Bordetella bronchiseptica in a patient with chronic lymphocytic leukemia. There was discrepancy between the in vitro sensitivity testing of the organism and subsequent clinical response to several antimicrobial agents. Human infection with B bronchiseptica is almost always associated with severe underlying disease and contact with an appropriate animal reservoir.

Treatment of Acute Lymphoblastic Leukemia with the Adenosine Deaminase Inhibitor 2′-Deoxycoformycin

Congenital deficiency of the enzyme adenosine deaminase (ADA, EC 3.5.4.4.) is associated with severe combined immunodeficiency disease characterized by marked lymphopenia and thymic involution.1 ADA catalyzes the deamination of adenosine and deoxyadenosine to inosine and deoxyinosine, respectively, and it has been proposed that the increased levels of deoxyadenosine associated with ADA deficiency lead to the selective accumulation of dATP by lymphoid cells, inhibition of DNA synthesis and cell death.2