S6b–e). In addition, B cell subsets developing in the NSG–BLT mice were compared to the populations in human blood. As described previously, there are higher ABT-263 chemical structure levels of immature and transitional B cells in the blood of NSG–BLT mice compared

to humans [37]. Together, these results suggest that irradiation is not necessary for B cell development but is required to obtain optimal number of B cells and for Ig production. We next evaluated the development of human innate immune cells in the BLT model established with or without irradiation conditioning (Supporting information, Fig. S7). The gating strategy used to define the human innate immune subsets is shown in Supporting information, Fig. S7a. At 16 weeks post-implant the development of human monocyte/macrophage (CD14+/CD33+), myeloid dendritic cells (mDC, CD11c+/CD33+) and plasmacytoid DC (pDC, CD123+/CD33+)

was assessed in the blood, spleen and bone marrow (Supporting information, Fig. S7b–d). Significantly higher percentages of human monocyte/macrophage were detected in the blood of NSG–BLT mice that had received irradiation compared to non-irradiated NSG–BLT mice, and there was a trend towards increased levels in the spleen and bone marrow, although these differences Autophagy signaling pathway inhibitor were not significant (Supporting information, Fig. S7b). The levels of mDC (Supporting information, Fig. S7c) and pDC (Supporting information, Fig. S7d) were similar in irradiated and

non-irradiated NSG–BLT mice. In addition, innate cell subsets developing in the NSG–BLT mice were comparable to the populations in human blood. Together, these results suggest that RG7420 irradiation conditioning of the recipient slightly enhances human macrophage development in NSG–BLT mice but is not necessary for mDC or pDC development. The standard implantation site for thymic and liver fragments in the BLT model is within the subcapsular space of the kidney. However, this procedure is considered survival surgery for the mice and is labour-intensive. As an alternative to the renal capsule, we tested whether implantation of thymic and liver fragments subcutaneously would support high levels of T cell development. NSG mice were irradiated with 200 cGy, implanted with 1 mm3 fragments of human fetal thymus and liver either in the renal subcapsular space or subcutaneously, and then injected i.v. with human HSC derived from the fetal liver. At 18 weeks post-implant the mice were evaluated for total human cell chimerism (CD45+ cells), for human T cell development (CD3+ cells) and for human B cell development (CD20+) in the blood and spleen (Fig. 4a–c). No significant differences were detected for the percentage of CD45+ cells in the blood and spleen (Fig.