CD4 and systemic lupus erythematosus: We found that the frequency of CD4+CD8+ thymocytes was significantly decreased, while the ratios of CD4+/DP and CD8+/DP were significantly elevated in IL-39 plasmid-treated recipients (Fig. 3A), indicating that IL-39 could exacerbate thymic damage in both lupus-like and scleroderma-like cGVHD models.