Elevated Erythrocyte Adenosine Deaminase Activity in Patients with Acquired Immunodeficiency Syndrome

Acquired immunodeficiency syndrome (AIDS) is an often fatal disease caused by a retrovirus frequently resulting in malignancy and/or opportunistic infection. Because the immune deficiency in AIDS is similar to that in some purine enzyme deficiencies, we measured erythrocyte adenosine deaminase (ADA) and purine nucleoside phosphorylase activities in patients with AIDS, heterosexual controls, and a high-risk asymptomatic population. We found that erythrocyte ADA activity was significantly elevated in patients with AIDS (40 ± 11 nmol/mg of hemoglobin per hr, mean ± SD) relative to heterosexual controls (25 ± 10, P < 0.001). We also measured ADA activity in a group of individuals at high risk for AIDS and found that approximately half had significantly elevated ADA activities (45 ± 4, P < 0.002) that correlated with the presence of antibody to the lymphadenopathy retrovirus. Purine nucleoside phosphorylase activity was relatively normal in patients with AIDS as well as in individuals at risk for AIDS. Increased ADA appears to be a diagnostic marker of AIDS and may be useful in conjunction with antibody to the AIDS-related retrovirus in detecting the presence of infection in asymptomatic high-risk individuals. These data also suggest that, in addition to the lymphocyte, the erythroid cell line may also be infected by the AIDS-related retrovirus.