1. TILs upregulate CD137 in an HIF-1α–dependent fashion.
 TILs upregulate CD137 in an HIF-1α–dependent fashion. A, Hif-1αfloxed-UBC-Cre-ERT2 mice homozygous for the CD45.2 allele were induced with tamoxifen for 5 days, checked for loss of HIF-1α, and 1 week later, their splenocytes were adoptively transferred to congenic C57Bl/6 mice carrying the CD45.1 allele and bearing an established MC38-derived subcutaneous tumor. Ten days later, spleens and tumors were surgically excised and their CD45.1+ and CD45.2+ lymphocytes differentially analyzed by FACS. Dot plots show the gating strategy on CD3+ T cells in the spleen and in the tumor as indicated. Representative histograms on CD45.1- and CD45.2-gated cells in the spleen and in CD3+ TILS (tumor) are presented. Dot graphs show CD137-specific MFI in CD3+CD4+ and CD3+CD8+ T cells taken from the tumors or the spleens in 3 adoptively transferred mice. WT, wild-type. B, experiments as in (A) but in this case Rag-/- mice bearing MC38 tumors for 4 days were adoptively co-transferred with CD45.1 HIF-1α–sufficient splenocytes from control mice pretreated with tamoxifen and with CD45.2 splenocytes from Hif-1αfloxed-UBC-Cre-ERT2 pre-induced with 4-hydroxytamoxifen (4-HT). Dot plots show the FACS gating strategy to distinguish CD45.1 positive and negative events between CD4 and CD8 TILs. Dot graphs represent the mean intensity of fluorescence specific for surface anti-CD137 immunostaining on CD4 and CD8 cells from gated CD45.1-positive and -negative TILs.
Asís Palazón et al. Cancer Discovery 2012;2:
©2012 by American Association for Cancer Research