Hypoxia-mediated downregulation of MHC class I expression impairs recognition and killing of tumor cells by CTLs.

Abstract

<p>(<b>A</b>) Hypoxic-grown MCA205-OVA cells with downregulated MHC class I expression were poorly recognized and killed by effector OT.1 T cells compared to normoxic controls. OVA expressing MCA205 tumor cells were grown in 3D cultures for 48h in 21% O₂ conditions. A subset of these cells were then moved to hypoxic (1% O2) conditions for an additional 24h. The hypoxic and normoxic spheroids were subsequently co-cultured with activated OT-I T cells. Tumor cells were identified by CellTracker staining (stained prior to co-culture) and cytotoxicity was assessed based on percent propidium idodide positive tumor cells. Each data point represents a replicate. Data is representative of 3 independent experiments. (<b>B</b>) Flow cytometry assessment of surface expression of MHC-SIINFEKL on OVA transfected MCA-205 cells. The tumor cells were grown as 3D spheroids for 48h in either 1% or 21% O₂ conditions. Each data point represents an independent experiment. n = 4. Error bars indicate SD. The significance of differences was analyzed by the Student’s t-test (two-sided); *p = 0.02, ** p = 0.003 (A), p = 0.005 (B).</p