Tumor-Evoked Regulatory B Cells Promote Breast Cancer Metastasis by Converting Resting CD4+ T Cells to T-Regulatory Cells

Pulmonary metastasis of breast cancer requires recruitment and expansion of T-regulatory cells (Treg) that promote escape from host protective immune cells. However, it remains unclear precisely how tumors recruit Tregs to support metastatic growth. Here we report the mechanistic involvement of a unique and previously undescribed subset of regulatory B cells. These cells, designated tumor-evoked Bregs (tBreg), phenotypically resemble activated but poorly proliferative mature B2 cells (CD19(+) CD25(High) CD69(High)) that express constitutively active Stat3 and B7-H1(High) CD81(High) CD86(High) CD62L(Low) IgM(Int). Our studies with the mouse 4T1 model of breast cancer indicate that the primary role of tBregs in…

• NI
  National Institutes of Health
• UO
  University of California, San Francisco
• NI
  National Institute on Aging
• NE
  National Eye Institute