Innate Response Activator (IRA) B Cells Reside in Human Tonsils and Internalize Bacteria In Vitro
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| Authors: | Nico Chiappini Rocco Cantisani Laura Pancotto Paolo Ruggiero Domenico Rosa Andrea Manetti Antonio Romano Francesca Montagnani Sylvie Bertholet Flora Castellino Giuseppe Del Giudice |
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| Institution: | 1. Novartis Vaccines and Diagnostics (a GSK company), Research Center, Via Fiorentina 1, Siena, Italy.; 2. Otorhinolaryngology Department, University Hospital Le Scotte, Strada delle Scotte 14, Siena, Italy.; 3. Department of Medical Biotechnologies, Infectious Unit, University Hospital Le Scotte, Strada delle Scotte 14, Siena, Italy.; COCHIN INSTITUTE, Institut National de la Santé et de la Recherche Médicale, FRANCE, |
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| Abstract: | Innate response activator (IRA) B cells have been described in mice as a subset of B-1a B cells that produce granulocyte/macrophage colony-stimulating factor (GM-CSF) and have been found in the spleen upon activation. In humans, identification, tissue localization and functionality of these lymphocytes are poorly understood. We hypothesized that IRA B cells could reside in human palatine tonsils, which are a first line of defense from infection of the upper respiratory tract. In the present work, we used flow cytometry and confocal microscopy to identify and characterize human IRA (hIRA) B cells in tonsils. We show that CD19+CD20+GM-CSF+ B cells are present in the tonsils of all the subjects studied at a frequency ranging between ~0.2% and ~0.4% of the conventional CD19+CD20+GM-CSF- B cells. These cells reside within the B cell follicles, are mostly IgM+IgD+, express CD5 and show phagocytic activity. Our results support a role for hIRA B cells in the effector immune response to infections in tonsils. |
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