Fig. 6

Soluble E-selectin enhances infiltration of PBMCs into tumor and tumor growth in NSG mice: a Human PBMC infiltration into breast tumor. Freshly isolated PBMCs were labeled with Calcein AM, followed by incubation with 100 nM sE-selectin for 15 min. After a brief washing to eliminate sE-selectin carryover, PBMCs (2 × 10⁷ cells) were infused into NSG mice bearing orthotopic breast tumors derived from MDA-MB-231 breast cancer cells (n = 4). Tumors were isolated 4 days after PBMC infusion and the numbers of Calcein-positive cells were counted by FACS. The histogram represents Mean ± SE (n = 4 mice). Frozen sections (5 μm) were stained with Hoechst 33342 (blue) to label nuclei. b Tumor growth following PBMC infusion. MDA-MB-231-luc cells was injected into mammary fat pad of NSG mice at day 0 and tumor growth was measured at day 10 and 16 to confirm similar growth rate between two groups. On day 18 and 25, human PBMCs (10⁷ cells) were infused via tail vein (red arrow) and tumor growth after the infusion was measured on day 22 and 29. Tumor growth was measured using bioluminescent imaging. The graph indicates photon flux from mice infused with PBMCs pre-incubated with saline (dashed line) or 100 nM sE-selectin (solid line). The data represent Mean ± SE (n = 5). c FACS analysis of human CD45+ leukocyte populations in the tumor. Tumors were harvested and single cell suspensions were labeled with human CD45, CD4, CD8, and CD68, and were analyzed by flow cytometry