Most cancer immunotherapies in development depend on the activity of T cells. However, the role of B cells in cancer immunology is not well understood. Two papers published in Nature reveal two opposing roles for B cells.
The paper from Stanford University show that B cells secrete IgG antibodies, triggering a cellular immune response. IgG antibody’ variable region recognizes tumour antigens, while its constant region interacts with the Fcγ receptor of dendritic cells (DCs). The DCs then extract tumour antigens and present them to T cells.
The paper from University of California San Diego show a different role for B cells. In prostate cancer, B cells express IgA, IL-10, and PD-L1 that suppress anticancer immune responses. Deleting B cells improves T-cell-based eradication of oxaliplatin-treated tumours.
It is not surprising that B cells play two opposing roles in cancer immunology. The immunosuppressive function of regulatory T cells (Tregs) and regulatory B cells (Bregs) has been noticed for decades. Several IDO inhibitors (indoximod, NLG919, INCB024360, etc.) are being developed to suppress Tregs. New drugs removing B-cell-mediated immunosuppression may come out in future.
 Nature. 2015, doi: 10.1038/nature14424.
 Nature. 2015, doi: 10.1038/nature14395.