Nod cg prkdcscid il2rgtm1wjl szj or nsg mice

All mice were maintained in the animal facility at UCLA. All experiments were performed in ethical compliance with the study protocol approved by the UCLA Animal Research Committee (ARC # 1996–058). Humanized bone marrow liver thymus (BLT) mice were constructed by the UCLA humanized mouse core using techniques described previously^{8 (link),61 (link)}. In brief, NOD.Cg-Prkdc^scid Il2rg^tm1Wjl/SzJ or NSG mice or C57BL/6 Rag2^−/−γc^−/−CD47^−/− or TKO mice^{58 (link)} were obtained from Jackson Laboratories and bred at UCLA. Male and female mice were age-matched and between 6 and 8 weeks old were irradiated with 270 rads, and then pieces of fetal thymus and liver tissue were transplanted under the kidney capsule. Mice were then injected intravenously with 5 × 10⁴ human fetal liver-derived CD34⁺ cells isolated by immunomagnetic separation.

Human immune system mice were generated by engraftment of cord blood-derived stem cells into immune deficient and irradiated mice. NOD.Cg-Prkdc^SCIDIl2rg^tm1Wjl/SzJ (or NSG) mice (Jackson Laboratory) at 3–4 weeks of age received a sublethal radiation dose of 125 cGY exposure in a RS 2000 small animal irradiator. Mixed donor human cord blood CD34⁺ stem cells (Stem Cell Technologies) were rapidly thawed, washed with PBS + 5% FBS solution and resuspended in a sterile Diprotin A (R&D Systems) solution prior to injection. Following irradiation, mice were injected i.v. with 1 × 10⁵ CD34⁺ cells per mouse. Prior to human immune system reconstitution, mice were housed in sterile bedding, received gamma-irradiated feed, and acidified (HCL) drinking water to reduce potential for environmental opportunistic infections. Reconstitution of human leukocyte populations was evaluated in peripheral blood by flow cytometry as we have previously described [21 (link)] using cell surface markers specific to human CD45, CD3, CD4, CD8 and CD14.