PrMCs derived in vitro from CD34⁺ adult hematopoietic PPPs are susceptible to R5-tropic HIV. (A) FMF analysis of prMCs was performed by gating on populations of CD117/IgE dual-positive cells derived from adult CD34⁺ hematopoietic PPPs in serum-free mast cell medium. The y-axis (% Max) represents the percentage of total gated cells at a given fluorescent intensity (represented on the x-axis). At 5 weeks in culture prMCs (≥ 95% total cells) expressed CD4, CCR5, and CXCR4 (HIV) viral receptors and coreceptors. Black lines note cell populations treated with antigen-specific antibody; white lines note cell populations treated with isotype-matched control. (B) PCR SS cDNA evidence that 5-week-old prMCs are strongly susceptible to R5-tropic (HIV_BAL) but only marginally susceptible to X4-tropic (HIV_TYBE) by PCR; LAD-2 control cells were susceptible to both HIV_BAL and HIV_TYBE. All experiments were performed a minimum of 3 times. All error bars represent standard deviation of the mean of replicate PCR reactions at each data point.