Tumor/Endothelium Crosstalk Attracts T Cells Figure 2. T lymphocytes migrate and localize to distant tumor deposits in the brain. (A) IHC for human CD3 in explants of tumors, propagated in the right cerebellum from subjects MB1277 and MB1323, 6 days after human T lymphocytes were injected into the ipsilateral caudate nucleus (x200). (B) Experimental tumors were established from the medulloblastoma cell line, Daoy, in the right caudate nucleus of SCID mice. Ten days later firefly luciferase-expressing T lymphocytes were stereotactically injected into the contralateral (left) caudate. T lymphocytes migrated within the brain to contralateral tumors in all experimental animals (n = 5) as judged by bioluminescence imaging. (C) The migration pattern of T lymphocytes was monitored over predefined gates placed over the left and right frontal lobes. Quantitative bioluminescence imaging indicated T lymphocyte efflux into the contralateral tumor gate in all experimental animals. (D) Immunohistochemistry for human CD3 performed on a subset of animals confirmed clustering of T lymphocytes at the tumor site. doi:10.1371/journal.pone.0020267.g002 PLoS ONE | www.plosone.org 3 May 2011 | Volume 6 | Issue 5 | e20267