Figure 3. Increased numbers of myeloid progenitor cells in aged CD137−/− and CD137L−/− mice. Bone marrow cells from 3 and 12 months old WT, CD137−/− and CD137L−/− mice were stained for lineage marker, IL-7R, CD117 and Sca-1. Cells were first gated on the progenitor cell region based on forward and side scatter. Then lineage marker−, IL-7R− cells were gated out for analysis of myeloid progenitors (CD117+ Sca-1−) and KSL (CD117+ Sca-1+) cells. (A) Gating strategy of KSL cells and myeloid progenitor cells. (B,C) Number of (B) KSL cells and (C) myeloid progenitor cells in 3 and 12 months old mice. Each group consisted of at least 3 mice. Data are representative of two independent experiments. *p<0.05.