Fig. 4

Comparison of the BI-12 xenograft tumor tissue to the original patient`s tumor. A HE-staining (top) shows highly similar tissue architecture between original tumor and xenograft tumor. Arrows indicate areas of tumor-associated stroma. Both tumors are highly positive for the HPV surrogate marker p16 (bottom); scale bars = 100 µm. B Indirect immunofluorescence staining for HNSCC stem cell marker ALDH1A1 and Treg marker FOXP3 (top) reveals ALDH1A1 + tumor cells in the original tumor and the xenograft tissue. FOXP3 was expressed only in the stromal areas of the patient`s tumor but not in the xenograft. B cell marker CD20 and T cell marker CD3 show B and T lymphocyte infiltration only in the human but not in the xenograft tumor; scale bars = 10 µm