B cell receptor signaling strength modulates cancer immunity.

Tumor-infiltrating B cells exert antitumor effects by producing antibodies against tumor-associated antigens. Conversely, B cells may promote tumors through the production of factors that dampen antitumor immunity. In this issue of the JCI, Bing Yang, Zhen Zhang, et al. investigated the roles of B cell receptor (BCR) signaling in antitumor immunity, focusing on the role of an Asia-specific variant of human immunoglobulin G1 (IgG1) containing a Gly396 to Arg396 substitution (hIgG1-G396R) in colorectal cancer (CRC). Epidemiological analysis revealed an association between hIgG1-G396R and progression-free survival in CRC. Human samples and mouse models of CRC showed plasma cells, as opposed to B cells, infiltrating the tumor microenvironment. Notably, patients with the hIgG1-G396R variant had increased CD8+ T cells, dendritic cells, and tertiary lymphoid structure density. These findings indicate that the hIgG1-G396R variant represses tumorigenesis by enhancing B cell responses, and suggest that modulating BCR signaling could improve the efficacy of immunotherapy in cancer.