The impaired number of circulating granulocyte/macrophage progenitors (CFU-GM) in human immunodeficiency virus-type 1 infected subjects correlates with an active HIV-1 replication.

In this paper we investigated the role played by human immunodeficiency virus type 1 (HIV-1) in the pathogenesis of peripheral blood (PB) cytopenias of AIDS patients. The in vitro growth of PB granulocyte/macrophage progenitors (CFU-GM) was investigated in 45 HIV-1 seropositive (+) individuals at different stages of the disease. The number of circulating CFU-GM was significantly (p < 0.01) lower in AIDS patients (stages WR V-VI) than in HIV-1(+) asymptomatic individuals (stages WR I-II). Moreover, the presence of gag p 24 in the plasma and/or viral isolation from PB mononuclear cells of HIV-1(+) individuals was inversely correlated (p < 0.01) with the number of circulating CFU-GM, irrespectively with the stage of the disease. Viral isolates obtained from one asymptomatic and four symptomatic HIV-1(+) individuals were tested on the in vitro growth of normal hematopoietic progenitor (CD34+) cells, purified from PB of healthy donors. All the different viral isolates showed a dose-dependent inhibition of CD34+ cells, in the absence of either productive or latent infection. This suppressive effect was completely reversed by preincubating the different viral isolates with a polyclonal anti-gp 120 antibody before adding to normal CD34+ cells. These findings suggest a direct involvement of active viral replication products in the progressive impairment of hematopoiesis, characteristic of HIV-1(+) individuals in spite of the lack of a productive or latent infection of CD34+ hematopoietic progenitors.