The landscape of the tumor-infiltrating B cell and its association with T-cell and tumor microenvironment in human cancers.

Abstract

76 Background: Compared to recent advances in our knowledge of T cell biology with success of immunotherapy, little progress has been made in understanding of the effects of B cells in tumor microenvironment and their interactions with T cells. Preclinical studies reported that B cells may have immune suppressive roles in tumor microenvironment via induction of T cell exhaustion. However, this association has not been shown in human tissues. We explored the landscape of tumor infiltrating B and T cells and their association with tumor microenvironment in various human cancers for which the FDA approved the use of immune checkpoint inhibitors. Methods: Expression patterns for 812 immune related genes from the TCGA database were utilized to define tumor infiltrating cells in 2951 patients with bladder urothelial carcinoma, renal clear cell carcinoma, skin cutaneous melanoma, lung squamous cell carcinoma, lung adenocarcinoma, and head and neck squamous cell carcinoma. Odds ratios (ORs) of the numbers of tumors with versus without activated B cell infiltration by the presence of activated CD8T cell infiltration were calculated. Results: Immune landscape of the six human cancers showed a consistent inverse association between tumor infiltrating activated B and CD8 T cells (OR = 0.18, p < 0.001). B cell infiltration was associated with increased expressions of immune checkpoints PD-L1, PD-1 and CTLA-4 and regulatory cytokines TGF-β, IL-10 and IL-35, which are known to be secreted by regulatory B cells. Angiogenic markers, such as angiopoietins, VEGF, MMP-9, CXCL10, CXCL11 and Tie2, showed differential expression patterns between B cell high and low groups. Conclusions: This is the first study that reports the inverse association between tumor infiltrating B and CD8 T cells in human tissues. The strong associations between B cell infiltration and increased expressions of suppressive cytokines and immune checkpoints suggest regulatory B cells may play a role in the T cell suppression in tumor microenvironment. Our results implicate that depleting B cells, leading to possible disinhibition of T cell activation, may be a future therapeutic option in potentiating T cell mediated immunity.