Effects of recombinant human granulocyte colony-stimulating factor on central and peripheral T lymphocyte reconstitution after sublethal irradiation in mice

Granulocyte colony-stimulating factor (g-csf) is one of the most critical cytokines used for the treatment of acute radiation syndrome (ars). in addition to the hematopoietic effects of g-csf on the differentiation and proliferation of myeloid progenitor cells,g-csf is also known to have immunomodulatory effects. the aim of the present study was to investigate whether g-csf could accelerate central and peripheral t lymphocyte recovery after a sublethal dose of irradiation. female balb/c mice were subjected to 6 gy of total body irradiation and then were treated with either 100 mg/kg g-csf or an equal volume of pbs once daily for 14 days. percentages of thymocyte subpopulations including cd4 - cd8 -,cd4 + cd8 +,cd4 + cd8- and cd4 - cd8+ t cells,peripheral cd3 +,cd4+ and cd8+ cells were analyzed by flow cytometry. recent thymic emigrants (rtes) were assessed by real-time polymerase chain reaction (pcr) using primers specific to the 257-bp t cell receptor rearrangement excision circles (sjtrecs). the proliferative capacity of splenic mononuclear cells upon exposure to cona was measured by using the cell count kit-8 (cck-8). g-csf treatment promoted thymocyte regeneration,accelerated the recovery of cd4 + cd8+ cells and increased the frequency of thymocyte sjtrecs. these effects were more prominent at early time points (day 28) after irradiation. g-csf also increased the rate of recovery of peripheral cd3 +,cd4+ and cd8+ cells and shortened the period of severe lymphopenia following irradiation. g-csf also increased the splenic mononuclear cell mitotic responsiveness to cona more than control-treated cells. our results show that g-csf accelerates t cell recovery through both thymic-dependent and thymic-independent pathways,which could be used to increase the rate of immune reconstitution after sublethal irradiation. © the author 2012. published by oxford university press on behalf of the japan radiation research society and japanese society for therapeutic radiology and oncology.