Research Of The Relationship Between Regulatory T Cells, IL-35, Trec And Agvhd After Allo-Hsct

[Background and Objective]Allogeneic hematopoietic stem cell transplantation (allo-lHSCT) is an effective treatment for hematologic malignancies. Graft versus host disease (GVHD) alter allo-HSCT is one of the important complications. It’s of great significance to find effective hiomarkeis to predict the occurrence of GVHI) and then prevent it on time. Regulatory T cells was first reported in1995. and named the CD4CD25regulatory T cells (Treg cells). Aferwards Foxp3(the forkhead/winged helix transcription) was found to be another characteristic sign of Treg cells and played an important role in inducing immune tolerance and maintaining homeostasis. IL-35is newly discovered in recent years secreted by Treg. which belongs to the family of cytokines H.12. Studies have shown that IL-35can inhibit CD4T effector cells (Teff) proliferation in vitro, and is related to the inhibitory function of Trey. As a judgment of thymic recent output. T cell receptor excision circles (TREC) play an important role in evaluating the patients’ immune reconstruction after allo-HSCT. And whether TREC imolve in the occurrence of GVHD has not vet fullv understood. In order to research the relationship between regulatory T cells (Tregs), IL-35. TREC and acute graft-versus-host disease (aGVHD) in clinical allo-HSCT recipients, we conducted a prospective analysis of peripheral blood Tregs, IL-35and TREC in23patients.[Methods]Peripheral blood samples were collected from23patients(17males and6females; age range,8-46years) who received allogeneic hematopoietic stem cell transplantation. Of these patients,13got acute graft-versus-host disease, the other10without aGVHD. According to Glucksber grading criteria, the aGVHD group was divided into I-II degree group and III-IV degree group. In addition,21healthy individuals were served as the control group. The percentage of CD4+CD25+Foxp3+Tregs in peripheral CD4+T cells was detected by flow cytometry. The relative expression of Foxp3mRNA transcripts and the TREC level in the mononuclear cells were detected by real time polymerase chain reaction (RT-PCR). And the level of IL-35in the plasma was got by Enzyme Linked Immunosorbent Assay (ELISA).[Results](1) The percentage of CD4+CD25+Foxp3+Tregs, the level of Foxp3mRNA transcripts and the level of IL-35in the recipients with aGVHD (n=13) were all significantly lower than those in patients without aGVHD (n=10) and the healthy people (n=21)(P<0.05). And after effective drugs treatment, the level of the three all increased than before.(2) Tregs decreased linearly with increasing grades of GVHD at onset. Tregs at onset of aGVHD predicted the response to the aGVHD treatment.(3) Paired analysis in aGVHD patients comparing Tregs at aGVHD onset to prior time points (7-14days) showed significantly decreased in the ratio of CD4+CD25+Foxp3+regulatory T cells and the level of Foxp3mRNA (P<0.05)(4) TREC levels were not detected in some patients. In negative group the TREC levels of7cases increased with time. And it’s much lower in patients than that in control group (P<0.05). Meantime the TREC level in positive group was lower than that in negative group without significant difference(P>0.05). Besides, there were no obvious correlation between TREC level and CD4+CD25+Foxp3+Treg ratio, Foxp3mRNA expression level (P>0.05) [Conclusion]The ratio of CD4+CD25+Foxp3+Tregs. Foxp3mRNA relative transcripts and the level of IL-35were all decreased in the patients with aGVHD which may have important prognostic value as a biomarker of acute GVHD. TREC level in some cases increased with time, which indicates that these patients regain immune reconstruction after allo-HSCT. The differences of TREC level in aGVHD positive and negative groups showed that TREC may involve in the occurrence of aGVHD.