Specific Aim 1. Study DcR3-induced T cell activation in SLE and RA. A. Patients and controls Patients with SLE and RA in Department of Internal Medicine, National Taiwan University Hospital will be studied. All patient meet the criteria of the American College of Rheumatologists for diagnosis of SLE and RA. As controls, 20 healthy age- and gender-matched volunteers will be used. All the studies including samples involving human is in accordance with institutional guidelines.