Adenosine deaminase and nucleoside phosphorylase activity in patients with immunodeficiency syndromes

Red cell adenosine deaminase (ADA) and nucleoside phosphorylase (NP) activities were measured in 62 patients with various immunodeficiency syndromes and in 67 adult and 37 infant controls. NP activity was found to be within the normal range (1206 ± 144 U/gHb in adults, 1266 ± 270 U/gHb in infants) in all but 4 patients who had NP deficiency and abnormal T-cell but normal B-cell function. The mean ADA activity was 36 U/gHb (with 95% confidence interval of 22.5 – 58.1 U/gHb) for normal adult controls ( n = 67) and 35 U/gHb (95% confidence interval 21.6 – 60.8 U/gHb) for infant controls ( n = 37). Red blood cell ADA activity of the patients showed great variability: Normal activity was found in patients with X-linked agammaglobulinemia, ataxia telangiectasia, and Wiskott-Aldrich syndrome. Six of 17 patients with combined immunodeficiency syndrome (CID) had ADA deficiency, and 7 CID patients had significantly elevated red cell ADA activity. Two identical twins with common-variable immunodeficiency showed red cell ADA activity of five to six times that of the normal controls; however, ADA activity of white cells and cultured skin fibroblasts was normal. Family members of these twin sisters had normal red cell ADA activity. It is not known if the elevated ADA activity observed in some patients with immune deficiency is directly related to the abnormal immune function.