The proportion of CD200+ cells in PBMC of SLE patients was significantly higher than that in HCs (Figure 1A, B), especially in the CD4+ T-cell population, the CD11c-CD123high plasmacytoid DCs, and the CD11c+CD123- myeloid DCs (Figure 1B; see Additional file 2), but not in CD8+ T cells, CD19+ B cells, CD38bright plasma cells (data not shown), or CD14+ monocytes (P > 0.05). This evidence concerns the gene CD200 and systemic lupus erythematosus.