Adenosine-producing regulatory B cells in head and neck cancer

Background Multiple mechanisms of immunosuppression have been identified in the tumor microenvironment including regulatory B cells (B reg ). Recently, we have shown that B reg suppress T cell function by production of adenosine (ADO). However, the autocrine effect of ADO on B cells and the role of B reg in head and neck cancer remains unclear. Methods Blood ( n = 42) and tumor tissue ( n = 39) of head and neck cancer patients and healthy donors ( n = 60) were analyzed by FACS. The effect of ADO on phenotype, intracellular signaling pathways, Ca 2+ influx and ADO production was analyzed in B reg and effector B cells (B eff ) by FACS, luminescence and mass spectrometry. The blockage of the ADO receptor A 2A was analyzed in a murine head and neck cancer model. Results ADO-producing B reg were found in tumor tissue and peripheral blood. ADO inhibited the intracellular Bruton’s tyrosine kinase (BTK) and Ca 2+ influx only in B eff . The inhibition of BTK by ibrutinib mimicked the effect of ADO, and ibrutinib reduced the production of ADO by downregulation of CD39 in vitro. The inhibition of ADO receptor A 2A significantly reduced tumor mass and increased B cell infiltration, in vivo. Conclusion Our data demonstrate the presence of a novel ADO-producing B reg population within the tumor microenvironment in mice and humans. A new model is proposed on how ADO-producing B reg can influence the function of B eff cells in healthy donors and cancer patients. Thus, the modulation of the ADO pathway in B cells may serve as a therapeutic approach for cancer patients.