The human thymus perivascular space is a functional niche for viral-specific plasma cells

plasma cells (PC) begin accumulating in the thymic perivascular space (PVS) where they constitutively produce IgG without the need for additional stimulation. These, thymic PC secrete almost exclusively IgG1 and IgG3, the two main complement-fixing effector IgG subclasses. Moreover, using antigen-specific ELISpot assays, we demonstrated that thymic PC include a high frequency of cells reactive to common viral proteins. Our study reveals an unrecognized role of the PVS as a functional niche for viral-specific PCs. The PVS is located between the thymic epithelial areas and the circulation. PCs located in this compartment may therefore provide internal protection against pathogen infections and preserve the integrity and function of the organ.