The limited ability of cytotoxic T cells to infiltrate solid tumors hampers immune surveillance and the efficacy of immunotherapies in cancer. Adenosine accumulates in solid tumors and inhibits tumor-specific T cells. Adenosine inhibits T cell motility through the A_2A receptor (A_2AR) and suppression of KCa3.1 channels. We conducted three-dimensional chemotaxis experiments to elucidate the effect of adenosine on the migration of peripheral blood CD8⁺ T cells from head and neck squamous cell carcinoma (HNSCC) patients. The chemotaxis of HNSCC CD8⁺ T cells was reduced in the presence of adenosine, and the effect was greater on HNSCC CD8⁺ T cells than on healthy donor (HD) CD8⁺ T cells. This response correlated with the inability of CD8⁺ T cells to infiltrate tumors. The effect of adenosine was mimicked by an A_2AR agonist and prevented by an A_2AR antagonist. We found no differences in A_2AR expression, 3′,5′-cyclic adenosine monophosphate abundance, or protein kinase A type 1 activity between HNSCC and HD CD8⁺ T cells. We instead detected a decrease in KCa3.1 channel activity, but not expression, in HNSCC CD8⁺ T cells. Activation of KCa3.1 channels by 1-EBIO restored the ability of HNSCC CD8⁺ T cells to chemotax in the presence of adenosine. Our data highlight the mechanism underlying the increased sensitivity of HNSCC CD8⁺ T cells to adenosine and the potential therapeutic benefit of KCa3.1 channel activators, which could increase infiltration of these T cells into tumors.

细胞毒性T细胞浸润实体瘤的能力有限，这会妨碍免疫监视以及免疫疗法在癌症中的功效。腺苷在实体瘤中蓄积并抑制肿瘤特异性T细胞。腺苷通过A _2A受体（A _2A R）抑制T细胞运动，并抑制KCa3.1通道。我们进行了三维化学趋化实验，以阐明腺苷对头颈部鳞状细胞癌（HNSCC）患者外周血CD8 ⁺ T细胞迁移的影响。在存在腺苷的情况下，HNSCC CD8 ⁺ T细胞的趋化性降低，并且对HNSCC CD8 ⁺ T细胞的影响大于对健康供体（HD）CD8 ^+的影响T细胞。这种反应与CD8 ⁺ T细胞不能浸润肿瘤有关。A _2A R激动剂可模拟腺苷的作用，而A _2A R拮抗剂可阻止腺苷的作用。我们发现在HNSCC和HD CD8 ⁺ T细胞之间，A _2A R表达，3'，5'-环状单磷酸腺苷丰度或蛋白激酶A 1型活性没有差异。相反，我们在HNSCC CD8 ⁺ T细胞中检测到KCa3.1通道活性降低，但表达未降低。1-EBIO对KCa3.1通道的激活恢复了HNSCC CD8 ⁺ T细胞在腺苷存在下的化学趋化能力。我们的数据强调了HNSCC CD8敏感性增加的潜在机制⁺ T细胞产生腺苷和KCa3.1通道激活剂的潜在治疗优势，这可能会增加这些T细胞向肿瘤的浸润。