IL-1β increases hematopoietic cells in the E11 AGM region. E11 AGM tissues were cultured for 3 days in the presence or absence of different doses of IL-1β. (A) Flow cytometric analysis showing the absolute number of cells per AGM positive for CD45, c-kit, or Mac1 after AGM explant culture (n = 5). (B) Number of CFU-G, CFU-M, and CFU-GEMM per E11 AGM explant cultured for 3 days in the presence of 0, 1, or 10 ng/mL IL-1β. Colonies were scored in triplicate cultures after 7 days of methylcellulose culture (n = 2). (C) Percentage of adult recipient mice repopulated with donor E11 AGM cells. E11 AGM explants were cultured in 0, 1, or 10 ng/mL IL-1β for 3 days, and cells were injected into irradiated recipients (1 embryo equivalent [ee]). At 4 months after transplantation, recipient peripheral blood DNA was analyzed for donor hematopoietic chimerism by semiquantitative PCR. Only mice with more than 10% donor chimerism were considered repopulated. Each column represents the number of mice repopulated per number of recipients transplanted (13 of 24, 9 of 13, and 4 of 12) with AGM explant cells cultured in 0, 1, and 10 ng/mL IL-1β, respectively). Combined results of 8 separate transplantation experiments. The error bars represent SEM.