肿瘤微环境在肿瘤生长、侵袭和转移中发挥了重要功能，是近年来肿瘤学研究前沿热点之一。其中，“转移前微环境”为肿瘤转移提供了适宜定居、存活和增殖的“土壤”，该假说已获得广泛的认可与极大的关注。B淋巴细胞是体内执行体液免疫功能的主要免疫细胞群体，其功能性细胞亚群较之T细胞等研究甚少，在肿瘤微环境中的功能尤其是参与转移前微环境的形成也鲜有报道。本研究通过建立小鼠乳腺癌原位种植瘤自发淋巴结转移模型，发现肿瘤引流淋巴结中B细胞大量聚集，而且体内实验证明B细胞功能缺陷小鼠淋巴结转移明显减少。我们将进一步研究肿瘤驯化的B细胞的表型特征，以期找到新的具有免疫调控功能的B细胞亚群。同时对肿瘤驯化的B细胞促进淋巴结转移的具体机制进行深入探讨，为B细胞参与肿瘤负向免疫调控提供新的机制，从而为肿瘤的临床治疗及新药物靶点的寻找提供新的启示。

As one of the hotspots in oncology research, tumor microenvironment plays critical roles in tumor growth, invasion and metastasis. Pre-metastatic niche is the microenvironment which preparing the 'soil' for tumor cell settlement, survival and proliferation in the metastatic organs. B lymphocytes mainly participant in humoral immunity and differentiate into plasma cells to secrete immunoglobin. However, compared with T cells, little is konwn about the systematic B cell subsets and their roles in the tumor microenvironment, especially in the formation of pre-metastatic niche. In this study, we used an orthotopic xenograft model of mouse breast cancer and found significant accumulation of B cells (named tumor-educated B cells) in the tumor draining lymph nodes (DLN). Notably, mice deficient in B cells showed reduced LN metastasis. Next, we aim to study the phenotype of B cells and find new regulatory B cell subsets. We also try to find out the underlying mechanism by which B cells promote LN metastasis.Our study may provide a new perspective for understanding of sophisticated regulating network of B cells in tumor immunity and offer new possibilities for diagnoses and therapy of cancer.