The effect of IL-10 on FL + IL-7 and KL + IL-7–stimulated growth of Lin⁻Sca-1⁺c-kit⁺ progenitor cells. A total of 500 Lin⁻Sca-1⁺c-kit⁺ cells was cultured in complete IMDM and predetermined optimal concentrations of cytokines as indicated. After 12 days of incubation, total cell numbers were counted (□) and B220 expression (▨) determined by flow cytometry. The number of B220⁺ cells and total cell numbers represent the mean (SEM) of three independent experiments. * <2,000 cells. The number of B220⁺ cells produced in response to FL + IL-10, KL + IL-7 and KL + IL-10 was 15,667 ± 6,641, 3,972 ± 1,239 and <500, respectively.