Defining HPV-specific B cell responses in patients with head and neck cancer.

Abstract

SUMMARYTumours can harbour significant numbers of B cells and plasma cells, however, little is known about the antigen specificity of intra-tumoral B cells1–8. Here we show that human papillomavirus (HPV)-specific B cell responses are detectable in HPV-positive head and neck cancers, with active production of HPV-specific IgG antibodies in situ. HPV-specific antibody secreting cells (ASCs) were readily detectable (~0.7-25% of IgG+ ASCs) in the tumour microenvironment (TME) with minimal bystander recruitment of influenza-specific cells, suggesting a localised and antigen-specific ASC response. HPV-specific ASC responses, which correlated with plasma IgG titres, were directed against the HPV proteins E2, E6, and E7, with E2-specific responses tending to be the most dominant. Using intra-tumoral B cells and plasma cells, we generated several HPV-specific human monoclonal antibodies, which exhibited a high degree of somatic hypermutation, consistent with chronic antigen exposure. scRNAseq analyses revealed the presence of activated B cells, germinal centre B cells, and ASCs within the TME. ASCs and B cells were preferentially localised in the tumour stroma, with well-formed clusters of activated B cells indicating ongoing germinal centre reactions. Overall, we show that antigen-specific activated and germinal centre B cells as well as plasma cells can be found in the TME. Our findings provide a better understanding of humoral immune responses in human cancer and suggest that tumour-infiltrating B cells could be harnessed for the development of novel therapeutic agents.