Evaluating the antitumor role of B cells in patients with non-small cell lung cancer.

Abstract

75 Background: The focus of immunotherapy has been on CD8 and CD4 tumor infiltrating lymphocytes (TILs), however, tumor infiltrating B cells (TIL-Bs) have been reported in tertiary lymphoid structures (TLS) with CD4 TILs, and both TIL-Bs and TLS correlate with NSCLC patient survival. While TIL-Bs have been identified in NSCLC patients, their function in the tumor microenvironment has been understudied with no focus on their role as antigen presenting cells (APCs) and their influence on CD8 and CD4 TILs. We hypothesize that TIL-Bs help generate potent, long-term immune responses against cancer by presenting tumor antigens to CD4 TILs. Methods: We used freshly isolated B cells from NSCLC patient tumor and tumor adjacent tissue to determine TIL-B function. We generated a specific in vitro antigen presentation assay to determine APC function and immunoregulation by TIL-Bs, and we correlated our findings with tumor-free survival. Results: We observed that the total number of B cells at the site of the tumor versus the tumor-adjacent tissue was increased compared to other immune subsets. Further, we observed three types of CD4 TIL responses when TIL-Bs presented autologous tumor antigens. There were activated responder CD4 TILs that proliferated when combined with TIL-Bs alone, which indicates stimulation with endogenous tumor antigens. There were antigen-associated responders that required exogenous autologous tumor lysate to elicit a CD4 TIL response, and there were patient CD4 TILs that did not respond to antigen presentation by TIL-Bs. Within the activated and antigen-associated responders, the TIL-B phenotype influenced the CD4 TIL phenotype; if the TIL-Bs were activated (CD69+CD27+CD21+), the CD4 TILs were T helper (anti-tumor) CD4 T cells and if the TIL-Bs were exhausted (CD69-CD27-CD21-), the CD4 TILs were T regulatory cells (pro-tumor). These data suggest that TIL-Bs influence the phenotype and function of CD4 TILs in NSCLC patient tumors. Conclusions: In conclusion, determining if TIL-Bs are activated or exhausted in NSCLC patients will determine the extent of their anti-tumor function in cancer. Ultimately, results from this study will help predict how to target TIL-B functions in future immunotherapies for NSCLC patients.