Role of thymic B cells in the development of thymus-derived regulatory T cell in vitro

•Thymic B cells in the condition of our experiments did not influence the generation of nTregs, but rather maintain their viability when activated by both activators.•Activated thymic B cells maintained the high percentage of nTreg generation or counteracted the decrease of this percentage observed in non-activated culture.•Both activators (LPS and IMQ) have the same effect in the process of nTreg generation by B cells.•The percentage of B cells was strongly increased in the conditions of our experiments\72 h in LPS and IMQ-supplemented medium.

The thymus contains a low frequency of B cells, about 0.1-0.5% of total population of thymocytes that were shown to contribute in thymic negative selection. The fact that B cells in the periphery have been contributed in the generation of the T regulatory cell compartment emerged the idea that this process may indeed be initiated firstly within the thymus. The results of this study revealed that activated thymic B cells maintained the high percentage of nTreg generation or counteracted the decrease of this percentage observed in non-activated culture, and both activators (LPS and IMQ) have the same effect in the process of nTreg generation by B cells. In addition, the activated cultures showed increase of the level of expression of Foxp3 transcription factor. In this study we confirmed that thymic B cells in the condition of our experiments did not influence the generation of nTregs, but rather maintain their viability when activated by both activators.