Mesenchymal stem cells induced anti‐inflammatory features in B cells from breast tumor draining lymph nodes

The immune‐modulatory effect of adipose‐derived stem cells (ASCs) on B cells in cancer has not been well elucidated. Herein, the interaction between B cells and ASCs isolated from the breast fat of either normal (nASCs) or breast cancer women (cASCs) was investigated. B cells derived from breast tumor draining lymph nodes were co‐cultured with nASCs or cASCs and B cells proliferation was assessed in direct and transwell assays. Moreover, B cells were co‐cultured with cASCs, nASCs or mesenchymal stromal cells of the tumor tissue (TSCs) and B cell cytokine production was assessed using flow cytometery. cASCs or TSCs were co‐cultured with either intact or B cell depleted lymphocytes and frequencies of CD25+FoxP3+ Tregs, IL‐10+ or IFN‐γ+CD4+ T cells were assessed. Results showed that co‐culture of B cells with ASCs in transwell chambers did not affect B cell proliferation. nASCs, however, was able to significantly reduce B cell proliferation in direct co‐culture experiments (P = 0.004). The frequencies of IL‐10+, TNF‐α+, IL‐2+, and IFN‐γ+ B cells were not significantly different in the co‐cultures of B cells with ASCs or TSCs. But the TNF‐α+/ IL‐10+ B cells ratio decreased in all co‐cultures, a reduction merely significant in B cell‐cASCs co‐culture (P = 0.01). The frequencies of CD4+ T cells subsets in either intact or B cell depleted lymphocytes did not undergo significant changes following co‐culture with ASCs or TSCs. Therefore, ASCs is capable of inhibiting B cell proliferation in a contact dependent manner and shifting the cytokine profile of B cells toward an anti‐inflammatory profile.