由于缺乏可靠和特异性的方法，监测高度动态和复杂的免疫反应仍然是一个巨大挑战。在这里，我们通过多孔海藻酸盐凝胶与化学酶亲和标记的合作，开发了一种监测肿瘤免疫反应级联反应的策略。该多孔凝胶中含有肿瘤相关抗原、佐剂和促炎细胞因子，用于在体内招募内源的树突状细胞（DCs）并促进其成熟。然后，利用Fucosyl转移酶（Fuct）的自催化作用，将成熟的DCs经Fucosyl转移酶（Fuct）修饰为带有GDP-富糖甘露糖转移酶（GDP-Fuc-Fuct）的DCs。获取的Fuct-DCs迁移到引流淋巴结（dLNs）后，DCs和T细胞之间的分子识别介导的相互作用通过Fuct催化的亲和标记，成功地装饰T细胞与GDP-Fuc-酯通过产生的化学键。结果，通过在dLNs和肿瘤中进行生物正交标记，可以通过生物正交标记技术在dLNs和肿瘤中识别活化的肿瘤特异性T细胞，为研究原位肿瘤免疫机制开辟了新途径。© 2023 Wiley-VCH GmbH.

Monitoring the highly dynamic and complex immune response remains a great challenge owing to the lack of reliable and specific approaches. Here, we develop a strategy to monitor the cascade of tumor immune response through the cooperation of pore-forming alginate gel with chemoenzymatic proximity-labeling. The macroporous gel that containing tumor-associated antigen, adjuvant and pro-inflammatory cytokine is used to recruit the endogenous DCs and promote their maturation in vivo. The mature DCs are then modified with GDP-fucose-fucosyltransferase (GDP-Fuc-Fuct) via the self-catalysis of fucosyltransferase (Fuct). After the migration of the obtained Fuct-DCs to the draining lymph nodes (dLNs), the molecular recognition mediated interaction of DCs and T cells leads to the successful decoration of T cells with GDP-Fuc-azide through the Fuct catalyzed proximity-labeling. As a result, the activated tumor-specific T cells can be identified via the bioorthogonal labeling in dLNs as well as tumors, pioneering an avenue for the study of tumor immune mechanism in situ.© 2023 Wiley-VCH GmbH.