In Vitro Induction, Phenotypic Identification And Immunoregulatory Activity Of Human Regulatory γδ TCells And Their Correlation With Systemic Lupus Erythematosus

γδT cells bearingγδTCR composed by y and 8 chains were different fromαβT cells, which were a minor part of T lymphocytes. Expressed both TCR and NK cell receptors,γδT cells hold a special position in antigen recognition and immune responses. Because of the limited diversity of TCR expression and the non-MHC restricted antigen recognition pattern,γδT cells were classified as innate immune cells. They existed in the front line of anti-tumor and infectious diseases and were involved in tumor immunosurveillance and host defense against pathogens invasion. Apart from their anti-infection and anti-tumor effects, more and more evidences indicated thatγδT cells also had immunoregulatory functions. In order to fully understand the biological function ofγδT cells and investigate the phenotype, mechanism and clinical significance ofγδregulatory subsets, in our study, we took autoimmune disease as the research model and explored the regulatory functions ofγδT cells through in vitro induction.Autoimmune disease is one kind of diseases closely related to self tolerance and balance of the immune system, which includes localized and systemic diseases. It is usually a systemic disease, and brings injuries to multiple organs. But the current therapy mainly aimed at the symptoms and complications other than their etiology, and with remarkable side effects. As a consequence, the most urgent question is to figure out the immune mechanisms of these diseases and find the most effective therapy of etiology.The most common autoimmune disease is systemic lupus erythematosus (SLE), which manifests by causing self disorder of the immune system and affecting multiple systems. In this study we focused on the number, subset compositions and functional phenotypes of peripheral bloodγδT cells, compared the differences of the above parameters between active SLE patients and healthy volunteers as the breakthrough point to explore the role ofγδT cells played in the pathogenesis of SLE. The results showed that compared to the healthy volunteers, the proportion of peripheral bloodγδT cells were dramatically decreased in SLE patients, especially in Vδ2 subset and with no significant change in Vδ1 and Vδ3 subsets. Moreover, as for the four functional subsets which were classified according to the expression of CD27 and CD45RA ofγδT cells, CD27+CD45RA- central memory y8 T cells subset were reduced significantly in SLE patients, which implicated the correlation of these subsets to SLE. Then, in order to identify the existence of regulatoryγδT cells and investigate their functions and mechanisms, we induced the peripheral bloodγδT cells in vitro following the induction conditions of the CD4 regulatory T cells (Tregs). Peripheral bloodγδT cells were stimulated with anti-TCRγδin the presence of rhIL-2 and rhTGF-βcombining with or without rhIL-10 for the in vitro induction. Similar to classical CD4+ regulatory T cells (CD4 Tregs), inducedγδTregs expressed transcriptional factor Foxp3, and displayed suppressive effects on the proliferation of autologous naive CD4 T cells, among which Vδ1 cells contributed most of immunoregulatory activity.. In order to further analyze the phenotypes and mechanisms of these subsets, we used the transcriptional factor Foxp3 as the standard marker to detect the expression of surface molecules correlated to the expression of Foxp3. After the expression analyses of several regulatory-associated molecules, we found Foxp3 was only expressed in CD27+Vδ1 cells, however, not all the CD27+cells expressed Foxp3. So we further examined the correlation of classical regulatory cell marker CD25 and Foxp3 as well as the correlation of CD25, CD27 and Foxp3 in the V81 T cells. Finally we confirmed the y8 Tregs possessed a phenotype of V81 CD27+CD25+, and they mediated their suppressive effects on the proliferation of naive CD4 T cells mainly through a cell-cell contact manner.As a summary, our studies preliminarily investigate the possible regulatory functions of y8 T cells in the SLE, we also have optimized a strategy for inducing regulatory y8 T cells in vitro, and elaborate on the mechanisms of their regulatory functions, which fully reveal a new function ofγδT cells, and might provide a theoretical basis and operational feasibility of the immunotherapy strategy based on the y8 T cells in autoimmune diseases.