Prolonged Thrombocytopenia Is Associated With Increases Of CD8+ CX3CR1+ Cells In The Bone Marrow After Allogeneic Hematopoietic Stem Cell Transplantation

Prolonged thrombocytopenia is a common complication after allogeneic hematopoietic stem cell transplantation(allo-HSCT),which is associated with a high mortality and poor prognosis. The aim of this study was to assess the impact of the CD8+CX3CR1+ T cells on the development and maturation of megakaryocytes in patients with the prolonged thrombocytopenia after allo-HSCT in order to identify the risk factors related to thrombocytopenia after allo-HSCT.

The changes in CD8+ T cells and their homing receptors CX3CR1, CXCR4 and VLA-4 in bone marrow of patients( N=89) with and without (N=94 ) prolonged thrombocytopenia following allo-HSCT and the impact of activated CD8+ T cells on apoptosis and ploidy of megakaryocytes in vitro ware determined. The percentage of CD8+CX3CR1+ T cells was significantly higher in prolonged thrombocytopenia patients than control (P<0.001).The increase in CD8+ T cells was not observed in peripheral blood. Patients with prolonged thrombocytopenia exhibited a marked increase in the number of low ploidy(≤8) megakaryocytes compared to those without(P<0.05). Depletion of CD8+ T cells increased apoptosis of megakaryocytes (P<0.05), which was corrected by reconstitution of CD8+ T cells (P<0.05). We demonstrated that prolonged thrombocytopenia is associated with increased expression of CX3CR1 and recruitment of CD8+ T cells into the bone marrow. Activated CD8+ T cells suppress apoptosis of megakaryocytes in vitro. Our findings shed light on the prolonged thrombocytopenia is associated with increases of CD8+ CX3CR1+ cells in the bone marrow after allo-HSCT patients.