In vivo evaluation of the anemia induced by azidothymidine (AZT) in a murine model of AIDS.

Azidothymidine (AZT) induces severe anemia in patients with acquired immune deficiency syndrome (AIDS). To evaluate the mechanism of anemia in immune-suppressed animals, a murine model of AIDS (MAIDS), caused by infection with LP-BM5 murine leukemia virus (LP-BM5 MuLV) was used at early and late stages of the disease. AZT-induced anemia was dose- and time-dependent. An increased percentage of erythroblasts in bone marrow was observed, with an increased ratio of early to late erythroblasts in both disease stages. Increases in splenic erythroid burst-forming units (BFUe) were observed in early-stage AZT-treated mice. Mean plasma erythropoietin (EPO) levels were increased by AZT in both groups in a dose-dependent manner and were inversely proportional to hematocrit values. These data suggest that the anemia induced by AZT stimulated a response by immature erythroid elements, but that the maturation or survival of early erythroblasts may be impaired.