Role of Thymic B Cells in the Development of Thymus-Derived Regulatory T Cells In Vitro

The thymus hosts a minor population of B cells, constituting about 0.1–0.5% of total thymocytes, which play a role in thymic negative selection. Peripheral B cells contribute to the generation of the regulatory T cell compartment, suggesting this process might originate in the thymus. Our study demonstrates that activated thymic B cells sustain the generation of natural regulatory T cells (nTregs) or mitigate the decline observed in non-activated cultures. Both lipopolysaccharide (LPS) and imiquimod (IMQ) effectively enhance nTreg generation. Additionally, activated cultures exhibit increased expression of the Foxp3 transcription factor. This study confirms that under experimental conditions, thymic B cells do not initiate nTreg generation but maintain their viability upon activation by LPS and IMQ.