Mobilization of CD34⁺ progenitor cells by granulocyte colony- stimulating factor in human immunodeficiency virus type 1-infected adults

We conducted a clinical trial to determine the feasibility of growth factor mobilization of CD34⁺ progenitor cells in human immunodeficiency virus type 1 (HIV-1)-infected individuals. Eight asymptomatic, HIV-l-infected adults (median CD4⁺ T-cell count, 415 cellsμL), received 480 μg/d of granulocyte colony-stimulating factor (G-CSF) for 6 days without evidence of vital activation. Despite concerns that HIV-1 might inhibit hematopoiesis, CD34⁺ cells were successfully mobilized to the periphery of all donors, independent of the baseline CD4⁺ T-cell count, and the status of antiretroviral therapy. Leukapheresis was performed on day 6, and yielded a median of 194 x 10⁶ CD34⁺ cells per leukapheresis (n = 7). CD34-enriched cells from the leukapheresia were predominantly myeloid-committed, but between 0.2% and 1.7% were primitive CD34⁺/CD38^- progenitors. A median of 21.7% of the mobilized CD34⁺ cells were dimly positive for CD4. Consequently, CD34⁺-enriched cells were purified on the call sorter (mean purity, 97.7% ± 2.4%; n = 7), and examined for HIV-1 DNA. Purified CD34⁺ cells from two of seven donors were polymerase chain reaction (PCR)-positive for HIV-1, but only from one of three samples from each donor. We conclude that G-CSF can safely mobilize CD34⁺ progenitor cells in HIV-l-infected subjects, and that these cells are suitable for consideration in gene- transfer strategies.