抗原特异性T细胞进入人类肿瘤对免疫治疗至关重要，但其潜在机制尚不明确。在此研究中，我们将高维空间分析与体外和体内模型相结合，研究了人类多发性骨髓瘤（MM）和其前体病态单克隆免疫球蛋白病（MGUS）中免疫浸润机制。聚集肿瘤生长是MM组织切片的一个特征，而不是MGUS组织切片的特征，这种生长模式在人化小鼠模型中得以复制。MM组织切片表现出内部病灶以及空间异质性，含有T细胞丰富和T细胞稀疏区域的共存，以及T细胞排斥区域的存在。体外研究表明，T细胞进入MM病灶是通过激动性信号和CD2-CD58相互作用调控的。在细胞移植后，抗原特异性T细胞定位于肿瘤部位，但需要原位DC介导的抗原呈递才能进入肿瘤。C型凝集素结构域家族9成员A阳性（CLEC9A +）DCs似乎是标记MM病灶中T细胞浸润梯度入口的的标志物，它们与T细胞因子1阳性（TCF1 +）T细胞的接近与疾病状态和风险状态相关。这些数据说明肿瘤相关DC和原位活化在促进MM中抗原特异性T细胞浸润方面发挥作用，并提供了关于肿瘤/免疫细胞在恶性进展中的空间改变的见解。

Entry of antigen-specific T cells into human tumors is critical for immunotherapy, but the underlying mechanisms are poorly understood. Here, we combined high-dimensional spatial analyses with in vitro and in vivo modeling to study the mechanisms underlying immune infiltration in human multiple myeloma (MM) and its precursor monoclonal gammopathy of undetermined significance (MGUS). Clustered tumor growth was a feature of MM but not MGUS biopsies, and this growth pattern was reproduced in humanized mouse models. MM biopsies exhibited intralesional as well as spatial heterogeneity, with coexistence of T cell-rich and T cell-sparse regions and the presence of areas of T cell exclusion. In vitro studies demonstrated that T cell entry into MM clusters was regulated by agonistic signals and CD2-CD58 interactions. Upon adoptive transfer, antigen-specific T cells localized to the tumor site but required in situ DC-mediated antigen presentation for tumor entry. C-type lectin domain family 9 member A-positive (CLEC9A+) DCs appeared to mark portals of entry for gradients of T cell infiltration in MM biopsies, and their proximity to T cell factor 1-positive (TCF1+) T cells correlated with disease state and risk status. These data illustrate a role for tumor-associated DCs and in situ activation in promoting the infiltration of antigen-specific T cells in MM and provide insights into spatial alterations in tumor/immune cells with malignant evolution.