Anti-CD4 treatment increases tumor-suppressive IL18Rahi CD8+ T cells

Anti-CD4 monoclonal antibody, a prominent immunomodulatory agent, elicits robust anti-tumor immunity in various cancers by increasing tumor-infiltrating lymphocytes and promoting CD8+ T cell reactivity against tumor cell-derived antigens. We conducted single-cell transcriptome analysis of anti-CD4-exposed lymphoid cells to investigate the detailed mechanism. Overall design: The model of mouse melanoma (B16F10) was used to study anti-CD4-induced change of lymphoid cells. We designed a regimen that utilizes cyclophosphamide treatment, adoptive transfer of tumor-specific T cells, and anti-CD4 treatment, a combination that synergistically increases the efficacy of adoptive T cell therapy. Three days after the B16F10 challenge, C57BL/6 mice sequentially received cyclophosphamide, ex vivo-primed Pmel-1 cells (melanoma-specific TCR-transgenic CD8+ T cells), and IL-2. A transient treatment (on day 10, 17, and 24) of anti-CD4 started seven days after cyclophosphamide treatment. Twenty-five days after the tumor challenge, cells from lymphoid tissues of the mice were subjected to single-cell transcriptome analysis. Two groups (3 mice each) received cyclophosphamide/Pmel-1 or cyclophosphamide/Pmel-1/anti-CD4. For each group, endogenous CD8+ T cells from three mice were pooled and used in the analysis.

抗CD4单克隆抗体（Anti-CD4 monoclonal antibody）是一类关键的免疫调节制剂，可通过增加肿瘤浸润淋巴细胞（tumor-infiltrating lymphocytes）数量、增强CD8+ T细胞（CD8+ T cell）对肿瘤细胞源性抗原的反应性，在多种癌症中诱导强效的抗肿瘤免疫应答。为探究其具体作用机制，本研究对经抗CD4单抗处理的淋巴细胞开展了单细胞转录组分析（single-cell transcriptome analysis）。

实验设计：本研究选用小鼠黑色素瘤（B16F10）模型，探究抗CD4单抗诱导的淋巴细胞变化。我们设计了联合治疗方案：环磷酰胺（cyclophosphamide）预处理、肿瘤特异性T细胞过继输注联合抗CD4单抗治疗，该方案可协同增强过继性T细胞疗法（adoptive T cell therapy）的疗效。在B16F10肿瘤细胞接种后第3天，C57BL/6小鼠依次接受环磷酰胺、体外预激活的Pmel-1细胞（黑色素瘤特异性T细胞受体转基因CD8+ T细胞）以及IL-2治疗。环磷酰胺给药7天后，于肿瘤接种后第10、17、24天对小鼠进行三次抗CD4单抗间歇性给药。在肿瘤细胞接种后第25天，收集小鼠淋巴组织中的细胞进行单细胞转录组分析。本实验分为两组，每组各3只小鼠：一组接受环磷酰胺+Pmel-1细胞治疗，另一组接受环磷酰胺+Pmel-1细胞+抗CD4单抗治疗。每组中，将3只小鼠的内源性CD8+ T细胞混合后用于后续分析。