IL-27 and SCF expand CD34⁻CD150⁺ LSK cells into multipotent myeloid progenitor cells.

(A-B) Enhanced expansion of CD34⁻ LSK cells by IL-27 and SCF. LSK cells from WT mice were divided into two populations according to the expression of CD34, CD34⁻ LSK, and CD34⁺ LSK cells, and each population (1 × 10²) was stimulated with IL-27 and SCF. One to 4 weeks later, these stimulated cells were analyzed by flow cytometry; representative dot plots of c-Kit and Sca-1 in the Lin⁻ population at 2 weeks are shown (A). Cell numbers of these stimulated cells were counted with time course (B). (C-E) Augmented expansion of CD34⁻CD150⁺ LSK cells by IL-27 and SCF. LSK cells were further divided into eight populations (F1-F8) according to the expression of CD34, CD150, and CD41 (C), and each population (50 cells) purified by sorting was stimulated with IL-27 and SCF. One to 4 weeks later, these stimulated cells were analyzed by flow cytometry. Representative dot plots of c-Kit and Sca-1 in the Lin⁻ population at 4 weeks are shown, and the cell number of the LSK cell population in these stimulated cells was counted with time course (D). LSK populations (1 × 10³) purified from primary or IL-27/SCF-expanded F1, F4, and F5 LSK cells were differentiated into myeloid cells by IL-3 and SCF, and cell number was counted (E). Data are shown as mean ± SEM (n = 3–4) and are representative of two to three independent experiments. *P < 0.05, ***P < 0.005.