To isolate such cells, BM cells excluded of lineage positive cells, were sorted for the CD117intermediateCD135+CD16/32lo surface expression [22]. These committed precursor cells STA-9090 in vitro were cultured in the presence

of Flt3L or Flt3L+GM-CSF for 8 days before loosely adherent cells were harvested for phenotypic analysis. The pro-DCs proliferated 5.1-fold under dual cytokines compared with 2.3-fold under Flt3L alone (Fig. 5). The DCs produced under dual cytokines compared with those under Flt3L alone were larger. They contained very few pDCs (CD45RA+) and CD8eDCs (Sirpα−), but were mostly CD8− equivalents (Sirpα+) (Fig. 5). Furthermore, the intracellular ROS level of the Sirpα+ subset of the DC progeny cultured Lenvatinib datasheet under dual cytokine conditions was higher than those cultured under Flt3L alone (Fig. 5). Taken together, these findings suggest that GM-CSF can divert FL-DC committed precursor cells to develop into GM-DCs. Since GM-CSF is also present in the steady state, albeit at lower levels [17], we investigated whether steady-state GM-CSF could exert any negative influence on CD8+ DC development in vivo. We firstly compared

the spleen DC composition between wild-type (WT) and GM-CSF deficient (GMKO) mice. Interestingly, we observed that spleen DCs of GMKO mice contained significantly higher numbers and percentages of CD8+ DCs, compared with WT mice (Fig. 6A). To confirm the above findings, we made mixed BM irradiation chimeras with equal numbers

of WT (Ly5.1) and βcKO (defective for GM-CSF signaling; Ly5.2) mice so that both types of DC developed in the same environment. In the reconstituted mice (4–6 weeks after BM transfer), both types of BM cells reconstituted approximately equally for CD11c+ cells and the total number of DCs of each origin was not significantly different (data not shown). However, the percentage and absolute number of CD8+ DCs of βcKO origin was higher compared with that of WT origin (Fig. 6B). Overall, these data indicate that disruption to GM-CSF signaling, whether by ligand or receptor deficiency, enhances the differentiation of CD8+ DCs. We hypothesized Terminal deoxynucleotidyl transferase that the fate of the DC subsets in vivo under elevated GM-CSF levels should mirror what we found in vitro. Indeed, a reduction in the proportion of pDCs and CD8+ DCs was observed in GM-CSF transgenic (GMtg) mice. GM-CSF transgenesis led to a great expansion of total splenocyte numbers (splenomegaly). We therefore enriched DC lineage by density centrifugation. Different DC subsets were sequentially gated, and the proportion of the total number of DCs per spleen was examined (Fig. 7A). Compared with WT controls, constitutive overexpression of GM-CSF reduced the proportion of pDCs by 5.7-fold, and CD8+ DCs by twofold. In contrast, a threefold increase in the proportions of mDCs, and a 1.2-fold increase in Ly6C−CD11b+ DCs were noted.