The origins of IgA-secreting cells in the acinar structures of the nasal turbinates [scRNA-seq]
Nasal vaccination elicits a humoral immune response that provides protection from airborne pathogens, yet the origins and specific immune niches of antigen-specific IgA-secreting cells in the upper airways remain unknown. Here, we define glandular acinus structures of the nasal turbinates as an immunological niche that recruits IgA-secreting plasma cells from the nasal-associated lymphoid tissues (NALT) in response to intranasal vaccination. Using intact organ imaging, we investigated the cellular events that support antibody-mediated immune responses in the mouse upper airways. Through visualization of antigen-specific T and B cells in the upper airways, we demonstrate that nasal vaccination induced extensive B cell expansion in the subepithelial dome (SED) of the NALT, followed by invasion into commensal bacteria-driven chronic germinal centers (GCs) in a T cell-dependent manner. Antigen-specific B cell response in the NALT required pre-expansion of cognate T cells, which initiate the immune response in the inter-follicular regions of the NALT, and occurred effectively in the presence of Monophosphoryl-Lipid A (MPLA), a synthetic, non-toxic TLR-4 agonist. NALT ablation and blockade of PSGL-1 demonstrated that intranasal vaccination generates IgA+ plasma cells that home to the nasal turbinates through the blood circulation where they are positioned primarily around glandular acinus structures. Thus, the glandular part of the nasal turbinate is an immunological niche that hosts NALT-derived IgA-secreting cells. These cellular events can be manipulated to design vaccines against inhaled pathogens or in the treatment of upper airway allergic responses. Overall design: Single-cell RNAseq of GFP B1-8hi B cells, five days after NP-OVA+MPLA intranasal immunization.