Objective To study histone H3 lysine 4 trimethylation (H3K4me3) in peripheral blood mononuclear cells (PBMCs) of systemic lupus erythematosus(SLE) patients.Methods PBMCs were isolated by density gradient centrifugation from 10 active SLE patients,7 inactive SLE patients and 8 healthy volunteers.Chromatin immunopreeipitation linked to mieroarrays (ChIP-chip) was used to profile the variations in H3K4me3 in CpG island regions in PBMCs of SLE patients and controls.ChIP-qPCR was used to validate the mieroarray results.To confirm correlations between H3K4me3 and gene expression,expression analysis by qRT-PCR was performed on three randomly selected H3K4me3 candidates.Results 413 (137 increased and 276 decreased H3K4me3) and 393 genes (112 increased and 281 decreased H3K4me3) displayed significant differences in H3K4me3 between active and inactive SLE when compared with healthy SUhjeets.The results of ChiP-qPCR were consistent with microarray.ConclusiOn There are significant differences in H3K4me3 profiling between SLE and healthy subjects.These novel candidate genes may be potential biomarkers for future therapeutic targets.The ChIP-chip technology can help further reveal SLE molecular mechanisms and discover new therapeutic targets.