Human PBL infiltrate and control tumor growth in huPBL-NSG animals. Six-8-week- old NSG mice were injected with saline alone or with human PBL (1x107) by intraperitoneal injection to produce huPBL-NSG animals. Mice were simultaneously implanted with 2x106 human prostate tumor cells (PC3 cell line) by s.c. injection and tumor growth was monitored over a 4 week period. (A) Final tumor volume (mm3) as measured percutaneously in the animal and corresponding images of tumors dissected from NSG and huPBL-NSG animals at 4 weeks. (B) Tumor growth curves for NSG and huPBL-NSG animals. (C) Recovered tumors were formalin-fixed, paraffin-embedded,sectioned, and stained with antibodies against either human PSCA (top panel, brown stain), to demonstrate tumor cells, or human CD45 (bottom panel, brown stain), to demonstrate infiltrating human leukocytes, and counterstained with Hematoxylin (blue stain). Magnification, x100. Values represent mean of three animals per group ± SD. *p < 0.05. Representative experiment, n = 5 replicate experiments.