Research on the Key T Cells and Cytokines of aGVHD after Allogeneic Hematopoietic Stem Cell Transplantation

Objective: Acute graft versus host disease(aGVHD) is due to one of the most important causes of treatment related mortality after allo-HSCT. T cells play the key roles in the development of aGVHD after allo-HSCT, and the different subsets play different roles. Research on the reconstruction of T cell immune function and its cytokines in the occurrence of aGVHD has become one of the hottest topic in aGVHD research. We investigated the key T lymphocyte subsets and its cytokines, to explore the relationship between the characteristics of T cell subsets and the process of aGVHD. We desire to find some biomarkers and establish early diagnosis index for aGVHD, furthermore find an important target for immunotherapy. Ultimately the strategy could reduce aGVHD related mortality and improve long-term disease-free survival in transplantation patients.

Methods: 64 patients were included in the study, from May 2013 to January 2014. Blood samples of these patients were monitoring every week. Treg, Th1 and Th17 cells number were detected by flow cytometry. Serum levels of IL-2, IL-6, IL-10, IL-17, TNF-a and IFN-γwere detected by flow cytometry (CBA). ELISA technique was used for the detection of serum TGF- β level.

Results: 36 patients (56.3%) suffered from II-IV aGVHD, and 10 cases (15.6%) among them was diagnosed of III°-IV° aGVHD. Before the onset of aGVHD, Treg, Th1, Th17 cells levels had no statistical difference between aGVHD patients and non aGVHD patients. In aGVHD patient, serum levels of IL-2 (P=0.0417) and TGF- β (P=0.0168) elevated in the early stage of aGVHD. IL-2 (P=0.0231), IL-10 (P=0.0089),TGF-β (P=0.0138) serum levels after aGVHD was significantly higher than that in non aGVHD patients, and Treg cellsnumber was significantly lower than that of patients without aGVHD (P=0.0150). Using ROC and logistic regression analysis, we found a composite biomarker panel (IL-2, IL-10 and Treg cell, which could optimally discriminated patients with and without aGVHD, the formula is: 1.656+0.103×IL-2|0.052 ×IL-10|0.037×Treg. ROC curve of composite panel is 0.89 (95% CI, 0.78-0.99, P=0.0002), which is larger than that of any single index.

Conclusion: Increased IL-2, IL-10, TGF-β serum levels in early stage after allo-HSCT can help to establish the clinical diagnosis of aGVHD, and which is expected to provide a clinical basis for further target immunotherapy. Treg cell level was negatively related to the onset of aGVHD. Furthermore, we found a composite biomarker panel (IL-2, IL-10 and Treg cell), which could optimally discriminated patients with and without aGVHD. It could provide a reliable basis for early diagnosis of aGVHD.