P15: The expression of Tc17 cells in thymoma accompany with autoimmune diseases or autoimmune disorders

Background: Thymoma is thymic epithelial cell tumor. Studies have shown that thymoma associated with autoimmune disorders and possible mechanisms of autoimmune diseases is the central immune tolerance and peripheral tolerance obstacles have resulted in the breaking of the autoimmune response activation and immune tolerance. Tc17 cells and Th17 cells have been shown play an important role in tumor and autoimmune diseases’ development process. This study test the distribution of Tc17cells in thymoma and the expression of RORγt in thymus of thymoma patients with myasthenia gravis (MG) or other autoimmune diseases, the frequency of Th17/Tc17 in PBMCs, to explore the expression of Th17/Tc17 cells in thymoma accompany with autoimmune diseases or autoimmune disorders.

Methods: In this study, grouped as follows: (I) thymoma non gravis group (Tm groups); (II) thymoma with MG group thymoma with MG (MG group); (III) thymoma with MG associated with other autoimmune diseases group or anti- nuclear antibodies abnormal elevation of the group (AD group), to analyze the basic differences between the groups. In this study, we examined the RT-PCR to detect RORγt in the thymoma tissue, immunohistochemical double staining method to detect Tc17 cells expression and localization in the thymoma tissue distribution expression Th17/Tc17 in PBMCs by flow cytometry [Interleukin (IL)-17-producing CD8+ cells as Thl7 cells and IL-17-producing CD4+ cells as Tcl7 cells], analysis of differential expression of three in each group thymoma; and explore of Th17/Tc17 expression.

Results: (I) Tm groups and AD group serum CD8+ cells was statistically significant (P<0.05), Tm groups and MG group serum CD4+ cells/CD8+ cells was statistically significant (P<0.05); Tm and MG/AD group serum, C3 statistically significant (P<0.05); Tm and MG/AD group serum, CRP statistically significant (P<0.05); Tm groups and AD group serum IgE cells was statistically significant (P<0.05); (II) in thymoma tissus, the level of Tc17 cells in MG/AD group was significantly higher than that in Tm, was statistically significant (P<0.05); (III) PCR tests RORγt mRNA levels, MG/AD group was significantly higher than that in Tm, statistically significant (P<0.05), according to the Osserman classification was statistically significant (P<0.05); (IV) in PBMCs’ Th17/Tc17 cells have risen trend in Tm groups and MG/AD group.

Conclusions: (I) CD8+ cells, CD4+/CD8+ T ratio, immunoglobulin, CRP and complement C3 levels can be used as indicators of evaluation of the role of the immune status of patients with thymoma; (II) RORγt mRNA is the key factors of Th17/Tcl7 cells differentiation, it may play an important role in thymoma accompany with autoimmune diseases or autoimmune disorders; (III) all these authenticate that Th17/Tcl7 cells are involved in the antitumor immunity and autoimmune disorders, which may offer evidence to a probability of immunotherapy.

Keywords: Thymoma; Tc17; Th7; autoimmune diseases