免疫识别的外源表位提供了抗癌免疫的基础。由于肿瘤微环境中细胞外三磷酸腺苷浓度较高，我们推测细胞外激酶（胞外激酶）可能活性失调，并在细胞表面蛋白上引入异常磷酸化位点。我们设计了细胞外激酶 CK2α 的细胞束缚版本，证明它在肿瘤相关条件下对细胞具有活性，并使用化学蛋白质组学工作流程分析了其底物范围。然后，我们证明小鼠会产生多反应性抗血清，以响应表面被 CK2α 过度磷酸化的同基因肿瘤细胞。有趣的是，这些小鼠针对这些抗原产生了 B 细胞和 CD4 T 细胞反应，但未能产生 CD8 T 细胞反应。这项工作提供了探测细胞外磷酸蛋白组的工作流程，并证明细胞外磷酸蛋白即使在同基因系统中也具有免疫原性。版权所有 © 2024。由 Elsevier Ltd 出版。

Foreign epitopes for immune recognition provide the basis of anticancer immunity. Due to the high concentration of extracellular adenosine triphosphate in the tumor microenvironment, we hypothesized that extracellular kinases (ectokinases) could have dysregulated activity and introduce aberrant phosphorylation sites on cell surface proteins. We engineered a cell-tethered version of the extracellular kinase CK2α, demonstrated it was active on cells under tumor-relevant conditions, and profiled its substrate scope using a chemoproteomic workflow. We then demonstrated that mice developed polyreactive antisera in response to syngeneic tumor cells that had been subjected to surface hyperphosphorylation with CK2α. Interestingly, these mice developed B cell and CD4+ T cell responses in response to these antigens but failed to develop a CD8+ T cell response. This work provides a workflow for probing the extracellular phosphoproteome and demonstrates that extracellular phosphoproteins are immunogenic even in a syngeneic system.Copyright © 2024. Published by Elsevier Ltd.