CD34(+) PROGENITOR CELLS FROM ASYMPTOMATIC PATIENTS ARE NOT A MAJOR RESERVOIR FOR HUMAN IMMUNODEFICIENCY VIRUS-1

Controversy exists as to whether hematopoietic progenitor cells are infected by human immunodeficiency virus-1 (HIV-1) in vivo. Most studies have focused on patients with acquired immunodeficiency syndrome (AIDS)/AIDS-related complex, and little data are available on asymptomatic patients with well preserved CD4(+) T-cell counts. To determine if CD34(+) hematopoietic progenitor cells are infected early in the course of HIV-1 disease, we evaluated 10 asymptomatic HIV-1 seropositive (HIV-1(+)) patients. The CD34(+) cell fraction was purified by a two-step procedure consisting of both affinity chromatography and fluorescence-activated cell sorting that resulted in a median purity of over 99%. Using conventional and nested polymerase chain reaction (PCR) assays, we evaluated the presence and frequency of HIV-1 proviral DNA. Both bone marrow mononuclear cells and CD34(-) cells from all 10 patients were strongly positive for the HIV-1 pol and/or gag gene sequences. In contrast, sorted CD34(+) cells from only two of 10 patients were positive, and the number of copies of proviral DNA in these samples was estimated to be from 2 to 5 per 250,000 cells. To test the in vitro functional capacity of CD34(+) progenitors, these cells were assayed in both methylcellulose and long-term stromal culture. We found no significant reduction in the number of colony-forming unit-erythroid (CFU-E), burst-forming unit-erythroid (BFU-E), or colony-forming unit-granulocyte macrophage (CFU-GM) colonies, or in the frequency of cobblestone area forming cells from limit dilution analysis in HIV-1(+) asymptomatic patients. Pooled methylcellulose colonies generated from CD34(+) cells were HIV-1(-) in nine of 10 samples. All progeny from long-term cultures of CD34(+) cells were HIV-1(-). We conclude that the CD34(+) hematopoietic progenitor compartment is not infected in the majority of asymptomatic HIV-1(+) patients, and that these cells may represent a suitable target for strategies designed to protect developing CD4(+) T cells from infection. (C) 1995 by The American Society of Hematology.