Significance of B10 cell in patients with thymoma complicated with myasthenia gravis

A subset of regulatory B cells in humans has been identified as B10 cell which has the function of secreting interleukin-10. We evaluated the significance of B10 cell in patients with thymoma complicated with myasthenia gravis. In this study, 156 patients diagnosed with thymoma were enrolled, FCM was used to detected the percentage of Breg/CD19⁺B cells and CD19⁺B cells/PBMC, ELISA to evaluate the serum concentration of the relevant immunological markers; purified CD19⁺B cells in tissues by MACS; gene and protein expressions of CD19 and IL-10 by Real-time PCR and Western-Blot; double immunofluorescence staining to detect the distribution of CD19 and IL-10 in thymus tissues. Thymoma patients without MG mainly display the types A and AB of thymoma, whereas the thymoma patients with MG mainly display type B (B1, B2 and B3) thymoma; AChR-Ab in Tm + MG group was the highest, with the progress of the disease, the percentage of Breg/CD19⁺B cells increased and B10/CD19⁺B cells decreased (p < 0.05); ROC curve showed that B10 had the greatest significance for the clinical directivity of Tm+MG and cut-off point = 0.55%; in accordance with the Con, Tm and Tm+MG group, the content of CD19⁺IL-10⁺B10 cells increased gradually (p < 0.05); meanwhile, the gene and protein expression levels of CD19 and IL-10 gradually increased in the same way. It is concluded that with the progress of thymoma, the infiltration of Breg in tumour tissue increases; however, as the severity of MG increases, the function of Breg (B10 cell) in peripheral blood decreases and the cut-off point is 0.55%.