Erythroblasts Promote the Development of a Suppressive Lymphocyte Phenotype via Treg Induction and PD1 Upregulation on the Surfaces of B-Cells: A Study on the Subpopulation-Specific Features of Erythroblasts

This study identifies the novel effects of soluble factors derived from murine erythroblasts on lymphoid cell phenotypes. These effects were observed following the treatment of splenic mononuclear cells with erythroblast-conditioned media received from both healthy mice and mice subjected to hematopoiesis-activating conditions (hypoxia, blood loss, and hemolytic anemia), suggesting a common mechanism of action. Using flow cytometry, we elucidated that erythroblast-derived soluble products modulate T cell differentiation by promoting Treg development and increasing PD-1 surface expression on B cells. The immunoregulatory potential of erythroblasts is subpopulation-dependent: CD45+ erythroblasts respond to hemolytic stress by upregulating the surface expression of immunosuppressive molecules PDL1 and Galectin-9, while CD45- erythroblasts primarily increase TGFb production. These findings highlight the regulatory role of erythroblasts in modulating immune responses.