Sharett Institute of Oncology, Hadassah Medical Organization, Jerusalem 91120, Israel.
J Immunol. 2012 Jan 15;188(2):632-40. doi: 10.4049/jimmunol.1101429. Epub 2011 Dec 7.
Trogocytosis, the transfer of membrane patches from target to immune effector cells, is a signature of tumor-T cell interaction. In this study, we used the trogocytosis phenomenon to study functional diversity within tumor-specific T cell clones with identical TCR specificity. MART-1(26-35)-specific CD8 T cell clones, which differed in their trogocytosis capacity (low [2D11], intermediate [2G1], high [2E2]), were generated from melanoma patients. Functional evaluation of the clones showed that the percentage of trogocytosis-capable T cells closely paralleled each clone's IFN-γ and TNF-α production, lysosome degranulation, and lysis of peptide-pulsed targets and unmodified melanoma. The highly cytotoxic 2E2 clone displayed the highest TCR peptide binding affinity, whereas the low-activity 2D11 clone showed TCR binding to peptide-MHC in a CD8-dependent manner. TCR analysis revealed Vβ16 for clones 2E2 and 2G1 and Vβ14 for 2D11. When peptide-affinity differences were bypassed by nonspecific TCR stimulation, clones 2E2 and 2D11 still manifested distinctive signaling patterns. The high-activity 2E2 clone displayed prolonged phosphorylation of ribosomal protein S6, an integrator of MAPK and AKT activation, whereas the low-activity 2D11 clone generated shorter and weaker phosphorylation. Screening the two clones with identical TCR Vβ by immunoreceptor array showed higher phosphorylation of NK, T, and B cell Ag (NTB-A), a SLAM family homophilic receptor, in clone 2E2 compared with 2G1. Specific blocking of NTB-A on APCs markedly reduced cytokine production by CD8 lymphocytes, pointing to a possible contribution of NTB-A costimulation to T cell functional diversity. This finding identifies NTB-A as a potential target for improving anti-cancer immunotherapy.
细胞融合，即靶细胞与免疫效应细胞之间的膜片转移，是肿瘤与 T 细胞相互作用的特征。在这项研究中，我们利用细胞融合现象来研究具有相同 TCR 特异性的肿瘤特异性 T 细胞克隆内的功能多样性。MART-1（26-35）特异性 CD8 T 细胞克隆，其细胞融合能力不同（低[2D11]，中[2G1]，高[2E2]），由黑色素瘤患者产生。对克隆的功能评估表明，具有细胞融合能力的 T 细胞的百分比与每个克隆的 IFN-γ和 TNF-α产生、溶酶体脱颗粒以及肽脉冲靶标和未修饰的黑色素瘤的裂解密切相关。高细胞毒性的 2E2 克隆显示出最高的 TCR 肽结合亲和力，而低活性的 2D11 克隆以 CD8 依赖性方式显示 TCR 与肽-MHC 的结合。TCR 分析显示克隆 2E2 和 2G1 的 Vβ16 和克隆 2D11 的 Vβ14。当通过非特异性 TCR 刺激绕过肽亲和力差异时，克隆 2E2 和 2D11 仍然表现出独特的信号转导模式。高活性的 2E2 克隆显示核糖体蛋白 S6 的磷酸化延长，这是 MAPK 和 AKT 激活的整合子，而低活性的 2D11 克隆产生较短和较弱的磷酸化。用相同的 TCR Vβ 通过免疫受体阵列对两个克隆进行筛选，与 2G1 相比，克隆 2E2 中 NK、T 和 B 细胞 Ag（NTB-A），一种 SLAM 家族同型受体的磷酸化水平更高。在 APC 上特异性阻断 NTB-A 可显著减少 CD8 淋巴细胞的细胞因子产生，这表明 NTB-A 共刺激可能对 T 细胞功能多样性有贡献。这一发现将 NTB-A 确定为改善抗癌免疫疗法的潜在靶点。
