Teleost IgD+IgM− B cells in gills and skin have a plasmablast profile, but functionally and phenotypically differ from IgM+IgD− B cells in these sites

• Published in: iScience 2023-08, Vol.26 (8), p.107434-107434, Article 107434
• Main Authors: Herranz-Jusdado, J. Germán, Morel, Esther, Simón, Rocío, Díaz-Rosales, Patricia, Tafalla, Carolina
• Format: Article
• Language: English
• Subjects: Biological sciences; Components of the immune system; Fish culture; Immunology
• ISSN: 2589-0042; 2589-0042
• DOI: 10.1016/j.isci.2023.107434

Although most B cells in teleost systemic compartments co-express IgM and IgD on the surface, cells exclusively expressing either of the two Igs are common in fish mucosal tissues, providing us with a unique opportunity to further characterize IgD+IgM− B cells, an intriguing B cell subset. Hence, we compared the phenotype of IgD+IgM− cells to that of IgM+IgD− B cells in rainbow trout gills and skin, also establishing the response of these subsets to immune stimulation. The transcriptional profile and secreting capacity of IgD+IgM− B cells corresponded to that of cells that have started a differentiation program toward plasmablasts, similarly to IgM+IgD− B cells. Yet, IgM+IgD− B cells retained high levels of surface MHC II and antigen-processing abilities, while these were much lower in IgD+IgM− cells, suggesting important differences in their antigen-presenting capacities. Our findings contribute to a deeper understanding of the enigmatic role of IgD in mucosal surfaces. [Display omitted] •IgD+IgM− B cells are an important non-IgT B cell subset in trout gills and skin•Gills and skin IgD+IgM− cells, as IgM+IgD− cells, have a plasmablast-like phenotype•IgD+IgM− cells have low surface MHC II expression and antigen-processing capacities•IgD+IgM− cells respond differently to immune stimulation than IgM+IgD− cells Biological sciences; Immunology; Components of the immune system; Fish culture