Sca‐1 + mesenchymal stromal cells inhibit splenic marginal zone B lymphocytes commitment through Caspase‐3

Mesenchymal stromal cells (MSCs) have been characterized as an important component of hematopoietic niche, which are capable of modulating the immune system through interaction with a wide range of immune cells. Marginal zone B cells, one main type of mature B lymphocytes, play a central role in eliciting antibody response against pathogens. However, how MSCs and its subpopulations regulate marginal zone B cells commitment is unknown yet. In this study, we assessed the contribution of Sca‐1 + MSCs on marginal zone B cells commitment. Our results showed that Sca‐1 + MSCs inhibit the commitment of marginal zone B lymphocytes. The inhibition was exerted through lowered Caspase‐3 expression. Furthermore, we found marginal zone B lymphocytes in spleen of Caspase‐3 knockout mice decreased and Caspase‐3 knockout Sca‐1 + MSCs accounted for the MZB lymphocytes decrease. In conclusion, our investigation provided clues about Sca‐1 + MSCs regulation on the commitment of marginal zone B cells through Caspase‐3 gene.