DNA is hypomethylated in T cells from SLE patients. It may lead to an increase in the expression of some genes that are usually silenced and, consequently, autoimmune phenomena may develop. On the other hand, this "unprotected" DNA could be the responsible for triggering anti-DNA antibodies. To find out the reason why this DNA hypomethylation is taking place, we have evaluated the expression level of different DNA methylases and demethylases. We have observed that two demethylases (MBD2 and MBD4) are overexpressed in T CD4+ lymphocytes of patients with SLE. We are now studying the effect the overexpression of these proteins may have in the expression regulation of different molecules involved in the immunologic response.

Antibodies against HERVs have been detected in patients suffering from some autoimmune diseases such as SLE, rheumatoid arthritis, Sjögren's syndrome, and multiple sclerosis. We mainly focus our research on trying to detect these antibodies in our patients affected with SLE. We have recently cloned some recombinant proteins specific for HERVs. We are simultaneously evaluating the transcription levels of several HERV proteins in T CD4+ lymphocytes from SLE patients.

The presence of the recently discovered retrovirus XMRV ("xenotropic murine leukaemia virus-related virus") is being currently studied in our lab in patients with SLE. This virus has been detected in blood samples of patients suffering from chronic fatigue syndrome (CFS). Interestingly, many patients with lupus also suffer from CFS. Based on these facts, with this project we establish as a hypothesis the possibility of finding XMRV DNA and RNA sequences in peripheral blood mononuclear cells from SLE patients, especially in those with CFS. We are nowadays setting up the already described XMRV-specific PCR and RT-PCR assays. We will also study the immunologic response of these patients against particular XMRV proteins.