FLT3+ DC inhibits immune rejection via interaction with Treg in liver transplantation.

• FLT3 + DC are decreased after liver transplantation (LT) in peripheral blood and liver tissue human and mouse. • After liver transplantation, proportion of FLT3 + DC changed dynamically in LT patients and mouse model. • There appears to be a restoration of the immune equilibrium as resulting from the feedback loop between Tregs and FLT3 + DCs in LT. Fms-like tyrosine kinase 3 (FLT3) is a receptor tyrosine kinase (RTK) primarily expressed in hematopoietic stem cells and dendritic cells (DCs). While FLT3 plays a critical role in the proliferation, development and maintenance of DCs, thus influencing immune responses under both normal and pathological conditions, there also exists some evidence that FLT3+DC may be involved with immune responses in liver transplantation (LT). In this study, results from single-cell sequencing data analysis revealed a clear relationship between FLT3+DCs and Regulatory T cells (Tregs) in liver tissue of LT recipients. In peripheral blood samples of LT patients, levels of FLT3+DCs were decreased post-LT-surgery, while Tregs were increased. In a LT mouse model, levels of FLT3+DCs in the liver and bone marrow exhibited an initial time-dependent decrease followed by an increase after LT surgery. Results as obtained with co-culture experiments using mature BMDCs and CD4+ T cells revealed fluctuations in Tregs in response to FLT3 inhibitors and the FLT3 ligand. These findings suggest that FLT3+DCs could emerge as a novel target for mitigating immune rejection in LT. [ABSTRACT FROM AUTHOR]