ry signaling. LFA-1 overexpression causes T cell autoreactivity in vitro and a lupus-like LY-411575 site disease in vivo. Interestingly, DNA hypomethylation in SLE affects sequences flanking the ITGAL promoter and an overexpression occurs on T cells from active SLE patients. Perforin 1 has also been identified as a gene whose transcription is increased in CD4+ T cells from active SLE patients and it seems to be due to demethylation of a conserved region located between the promoter and upstream enhancer. This aberrant overexpression of PRF1 in CD4+ T cells may contribute to the killing of autologous monocytes/macrophages by T cells observed in SLE. Killer cell Ig-like receptor gene family is also methylation-sensitive in human T cells. Less methylation of the KIR2DL4 promoter, for example, has been detected in SLE patients Although KIRs are preferentially expressed on NK cells, T cells from lupus patients have higher levels of KIR genes and their expression seems to be proportional to disease activity. The expression of some B-cell costimulatory molecules on CD4+ T cells is also affected in SLE. This is the case of CD70 and CD40LG. CD70 gene encodes a member of the tumor necrosis factor which regulates B-cell activation and immunoglobulin synthesis. The overexpression of CD70 found on T cells from patients with active SLE has been shown to overstimulate the production of IgG. CD40LG is located in X-chromosome and it has B-cell costimulatory functions resembling those of CD70. Women with SLE have 
been shown to overexpress CD40LG on CD4+ T cells which, in turn, also overstimulate B cells to produce IgG. The study of the expression of ITGAL, PRF1, KIR2DL4, CD70, and CD40LG genes in SLE patients was first prompted by the observation that these genes were overexpressed when DNA hypomethylation was induced in vitro with DNA methylation inhibitors. Several authors are currently performing genome-wide DNA methylation studies directly in CD4+ T cells or white blood cells from SLE patients. These works have been conducted in the general SLE population and in monozygotic twins discordant for the disease. This way, the promoters of other genes have also been proved to be hypomethylated. In the present work, we focused our attention on ITGAL, PRF1, KIR2DL4, CD70, and CD40LG and we investigated for the first time their simultaneous expression. Furthermore, we performed correlation analyses of the transcript expression of these genes with the global DNA methylation status and the levels of several DNA methylation enzymes. Patients and Methods Patients Data were collected from 35 Caucasian individuals who suffered from SLE. An ethnically matched random healthy control population was also included in the study. Subjects’ written consent was obtained according to the Declaration of Helsinki, and the design of the work conformed to standards currently applied in Spain. All the SLE patients fulfilled at least four of the American College of Rheumatology criteria. Methods Isolation of peripheral blood mononuclear cells and CD4+ T cells. A total of 20 mL of ethylenediaminetetraa- cetic acid -K3-preserved venous peripheral blood were withdrawn from both patients and controls. Peripheral blood mononuclear cells were obtained by Hystopaque-1077 density gradient centrifugation. CD4+ T cells were isolated by negative selection with the CD4+ T Cell Isolation Kit II using a cocktail of biotin-conjugated monoclonal antibodies against CD8, CD14, CD16, CD19, CD36, CD56, CD123, TCRc/