CD19+IL-10+ regulatory B cells affect survival of tongue squamous cell carcinoma patients and induce resting CD4+ T cells to CD4+Foxp3+ regulatory T cells

Objectives: Increase of regulatory T cells (Tregs) in the tumour microenvironment predicts worse survival of patients with various types of cancer including tongue squamous cell carcinoma (TSCC). Recently, the cross-talk between Tregs and regulatory B cells (Bregs) has been shown in several tumour models. However the relevance of Bregs to tumour immunity in humans remains elusive. Our objective was to investigate the distribution and function of Bregs in TSCC microenvironment. Methods: Double staining (Bregs: IL10/CD19 and Tregs: Foxp3/CD4) was performed on tissue sections of 46 TSCC, 20 metastasis lymph nodes, and tumour adjacent normal tissue. Flow cytometry analysis was used to detect the Bregs from magnetic bead-sorted B cells after co-culture with TSCC cell lines, and Tregs from sorted CD4 + CD25-T cells after co-culture with stimulated B cells. Results: The immunohistochemical results showed that the frequency of Bregs/CD19+ B in TSCC (0.80% ± 0.08%) was significantly higher than adjacent normal tissue (0.52% ± 0.04%; P < 0.01). And the increase of Bregs in TSCC microenvironment was related to Tregs and predicts worse survival in patients. Cytological experiments indicated that frequency of Bregs increased after co-culture with TSCC cell line and that the induced B cells converted CD4 + CD25-T cells into Tregs. Conclusion: The increased expression of Bregs in the TSCC microenvironment plays a significant role in the differentiation of resting CD4 + T cells and influenced the prognosis of TSCC patients.