Immune indicators analysis in 282 patients of thymoma with autoimmune diseases

Objective To compare the difference of immune indices and T lymphocyte subsets in patients with simple thymoma, thymoma combined with myasthenia gravis or other autoimmune diseases, analyze the immune characteristics of patients with thymoma combined with or without autoimmune diseases. Methods Retrospective analyze thymoma surgical cases in cardiothoracic surgery of Tianjin Medical University General Hospital from January 2014 to December 2018. A total of 282 patients with thymoma were included in the analysis, including 66 patients with simple thymoma, 188 patients with myasthenia gravis, and 28 patients with other autoimmune diseases. Patients were grouped by combining with MG or autoimmune diseases. Age, sex, pathological type, immune indexes (including IgG, IgA, IgM, IgE, C3, C4, CRP, circulating immune complexes, anti-nuclear antibodies), T cell subsets (including CD4+ T cells, CD8+ T cells, Th1, Th2, Th17 and Treg) were analyzed. Results The results showed that thymoma with autoimmune diseases and antinuclear antibodies positive were more likely to occur in female patients. Types B1, B2 and B3 thymomas were more likely to be associated with MG. Immune index analysis showed that IgG increased (P=0.008) and C3 decreased (P=0.007) significantly in patients of thymoma with MG or autoimmune diseases, they were the most significant immune indicators. CRP content in thymoma with MG was significantly lower than that in simple thymoma (P=0.004). the content of circulating immune complexes was higher in patients of thymoma with autoimmune diseases (P=0.03). IgG, IgE and circulating immune complexes increased significantly (P<0.05) and C3 decreased significantly (P=0.03) in thymoma patients with anti-nuclear antibody positive. T lymphocyte subsets analysis showed that CD4+ T lymphocyte, CD8+ T lymphocyte, CD4+ /CD8+ , Th1 cell and Th2 cell had no statistical significance. Thymoma patients with MG and autoimmune disease had higher Th17 content and higher Th17/Treg ratio, while Treg cells content decreased. Conclusion Women with thymoma were more likely to have autoimmune diseases and type B thymoma was more likely to have MG. The most significant immune indices were IgG and C3. The increase of IgG and the decrease of complement C3 were related to the type of immune diseases. The increase of Th17 cells and the decrease of Treg cells were related to the thymoma with autoimmune diseases. Key words: Thymoma; Autoimmune diseases; Myasthenia gravis; T lymphocyte subsets