Leukotriene B₄ (LTB₄) receptor 1 (BLT1) is a chemotactic G protein-coupled receptor expressed by leukocytes, such as granulocytes, macrophages, and activated T cells. Although there is growing evidence that BLT1 plays crucial roles in immune responses, its role in dendritic cells remains largely unknown. Here, we identified novel DC subsets defined by the expression of BLT1, namely, BLT1^hi and BLT1^lo DCs. We also found that BLT1^hi and BLT1^lo DCs differentially migrated toward LTB₄ and CCL21, a lymph node-homing chemoattractant, respectively. By generating LTB₄-producing enzyme LTA₄H knockout mice and CD11c promoter-driven Cre recombinase-expressing BLT1 conditional knockout (BLT1 cKO) mice, we showed that the migration of BLT1^hi DCs exacerbated allergic contact dermatitis. Comprehensive transcriptome analysis revealed that BLT1^hi DCs preferentially induced Th1 differentiation by upregulating IL-12p35 expression, whereas BLT1^lo DCs accelerated T cell proliferation by producing IL-2. Collectively, the data reveal an unexpected role for BLT1 as a novel DC subset marker and provide novel insights into the role of the LTB₄-BLT1 axis in the spatiotemporal regulation of distinct DC subsets.

白三烯 B ₄ (LTB ₄ ) 受体 1 (BLT1) 是一种趋化 G 蛋白偶联受体，由白细胞（例如粒细胞、巨噬细胞和活化的 T 细胞）表达。尽管越来越多的证据表明 BLT1 在免疫反应中发挥着至关重要的作用，但它在树突状细胞中的作用仍然很大程度上未知。在这里，我们鉴定了由 BLT1 表达定义的新 DC 子集，即 BLT1 ^hi和 BLT1 ^lo DC。我们还发现 BLT1 ^hi和 BLT1 ^lo DC 分别差异性地向 LTB ₄和 CCL21（一种淋巴结归巢化学引诱剂）迁移。通过生成LTB ₄产生酶LTA ₄ H 敲除小鼠和CD11c启动子驱动的Cre重组酶表达BLT1条件敲除（BLT1 cKO）小鼠，我们发现BLT1 ^hi DC的迁移加剧了过敏性接触性皮炎。综合转录组分析显示，BLT1 ^hi DC 通过上调 IL-12p35 表达优先诱导 Th1 分化，而 BLT1 ^lo DC 通过产生 IL-2 加速 T 细胞增殖。总的来说，这些数据揭示了 BLT1 作为新型 DC 子集标记物的意想不到的作用，并为 LTB ₄ -BLT1 轴在不同 DC 子集的时空调节中的作用提供了新的见解。