Abstract – Overview This program project is an exploration of patients with Systemic Lupus Erythematosus who are in long term clinical remission on no corticosteroid or immunosuppressive medication. We will study blood immune cells at the single cell level exploring distribution of cellular subsets and transcriptional, epigenetic and proteomic profiles, as well as the repertoire of naive and memory B cells reactive with nuclear antigens. We will explore brain function in these patients to determine if there is ongoing inflammation in the central nervous system in some patients despite a lack of inflammation in the periphery. Given the now recognized interplay of the immune system and the brain, we will seek correlations between immune cell profile and brain function. As approximately 25% of patients in remission can be expected to relapse over 5 years, we will seek predictors of relapse. These studies should teach us about patient heterogeneity, novel states of immune or brain homeostasis, and predictors of sustained remission or flare.