Background:Age-associated B cells (ABCs) constitute a B cell subset, defined as CD19+CD21−CD11c+, that expands continuously with age and accumulates strongly in individuals with autoimmune and/or infectious diseases. In humans, ABCs are principally IgD−CD27−double-negative (DN) B cells. Data from murine models of autoimmunity, implicate ABCs/DN in the development of autoimmune disorders. T-bet, a transcription factor which is highly expressed in these cells, is considered to play a major role in various aspects of autoimmunity, such as the production of autoantibodies and the formation of spontaneous germinal centres.Aims of the study:Despite the available data, the functional features of ABCs/DN and their exact role in the pathogenesis of autoimmunity remain elusive. This project focuses on the investigation of the role of ABCs/DN in the pathogenesis of systemic lupus erythematosus (SLE) in humans, as well as the effects that various pharmacological agents may have on these cells.Methods:Samples from patients with active SLE will be used to enumerate and immunophenotype - via flow cytometry - the ABCs/DN found in the peripheral blood of the patients. Transcriptomic analysis and functional assays for the cells, both before and after in vitro pharmacological treatments, will also be performed.Anticipated benefits:The results of the study are expected to allow characterization of the pathogenetic role of ABCs/DN in SLE and could probably contribute, following careful association with the clinical state of the patients, towards the discovery and validation of novel prognostic and diagnostic markers of disease.