Impact of <scp>G</scp> ‐ <scp>CSF</scp> on Donor <scp>TCR</scp> Clonal Diversity and <scp>T</scp> Cell Function During Donor <scp>HSC</scp> Mobilisation

Recombinant granulocyte colony-stimulating factor (G-CSF) is widely used to mobilise donor stem cells into peripheral blood for allogeneic haematopoietic stem cell transplantation (allo-HSCT). Studies have shown that G-CSF may reduce the incidence of acute graft-versus-host disease (aGVHD) following allo-HSCT by modulating T cell function. However, the patterns and mechanisms by which G-CSF regulates T cell function remain unclear. In this study, we used RNA sequencing combined with T cell receptor (TCR) immune repertoire sequencing to discover that G-CSF mobilisation leads to a reduction in donor TCR clonal diversity, downregulation of genes associated with TCR recombination, suppression of multiple antigen presentation processes, and varying degrees of downregulation in multiple T cell function-related signalling pathways. The results suggest that the pathway by which G-CSF mediates a low incidence of GVHD after allo-HSCT is by interfering with donor TCR recombination and antigen presentation processes, resulting in suppression of multiple T cell functions.