To B or not to B in NSCLC: Functional characterization of B cells in the TME of NSCLS patients 3076

Abstract Description The presence of tumor-infiltrating B-cells is associated with survival in several solid tumors, including non-small cell lung cancer (NSCLC). However, B-cells in the tumor microenvironment (TME) exhibit both anti- and pro-tumorigenic roles, depending on the cellular and signaling context within the TME. Identifying and characterizing these phenotypes could be pivotal for modulating B-cell responses toward anti-tumor immunity. We analyzed high-dimensional protein and RNA expression data from B cells derived from lung, blood, and tumor samples of NSCLC patients. Clinical samples were analyzed through surface marker screening and flow cytometry to evaluate protein surface marker expression on TME B cells. Single-cell RNA sequencing was performed on sorted B cells from matched tumor and lung samples, and multiplex immunofluorescence (mIF) was used to study spatial localization and marker expression in tumor and adjacent lung regions of FFPE samples. Our study identified four B-cell subtypes within the NSCLC TME: plasma cells, memory B cells, germinal center (GC) B cells, and naive B cells. Differential expression of 11 markers on TME B cells was validated compared to those from lung and PBMCs. Notably, CD55 displayed differential mRNA and protein expression, with mIF data showing increased CD55 expression in GC areas of tertiary lymphoid structures (TLSs). This highlights CD55’s potential role in B-cell functions within the TME. Funding Sources Austrian Research Promotion Agency (FFG) Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)