Role of CD4+CD25+highFoxp3+CD62L+Regulatory T Cells and Invariant NKT Cells in Human Allogeneic Hematopoietic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (HSCT) is the treatment of choice for some hematological diseases; however, graft-versus-host disease (GVHD) is still one of the most important and deleterious complications. Regulatory T cells and iNKT cells can decrease the incidence and severity of GVHD, while preserving the graft-versus-tumor response. In order to analyze the relationship between the transfused dose of these cells, the presence of GVHD and survival, 15 normal donors and 15 patients with hematological diseases who underwent allogeneic HSCT from HLA-identical siblings were studied. The mobilization and infused doses of v alpha 24-v beta 11(iNKT cells) lymphocytes and CD4+CD25+FoxP3+, CD4+CD25+FoxP3+CD62L+, regulatory T cells were analyzed. All patients were conditioned with busulfan and cyclophosphamide and received cyclosporine and methotrexate as GVHD prophylaxis. iNKT and FoxP3 cells were mobilized after G-CSF administration. Acute GVHD was present in 9 of 15 (60%) and cGVHD in 7 of 13 (54%) patients. Patients who received a dose <0.6 x 10(6)/kg of iNKT cells and >4 x 10(6)/kg of FoxP3 had better disease-free survival and overall survival. Individuals transfused with >1.1 x 10(6)/kg of FoxP3+ CD62L+ Treg cells had better overall survival. In conclusion, iNKT and Treg cells are mobilized with G-CSF in healthy donors and the dose of iNKT cells and FoxP3 and CD62L+ regulatory T cells is of clinical importance in human HSCT.