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. This evidence concerns the gene CD19 and thymoma.