CD4 and systemic lupus erythematosus: In order to further investigate the relationship between H3K4me3 and DNA methylation at the CREMα promoter in SLE CD4+ T cells, we examined the level of DNA methylation within the CREMα promoter in CD4+ T cells from the aforementioned 20 SLE patients via MeDIP and real-time PCR, and proved that H3K4me3 enrichment was negatively correlated with DNA methylation level at the CREMα promoter in SLE CD4+ T cells (Fig. 5a, Additional file 1: Table S2).