Neutrophils are sentinel cells of the innate immune system with a primary role of clearing extracellular pathogens. The release of weblike structures decorated with granular proteins called neutrophil extracellular traps (NETs) has recently been implicated in the pathogenesis of inflammatory and autoimmune diseases. Indeed, NETs may represent an important source of autoantigens and immunostimulatory proteins in systemic lupus erythematosus (SLE). In this chapter, we describe protocols to isolate human peripheral neutrophils, to generate and isolate NETs, and to detect SLE antigens in NETs using immunofluorescence and immunoblot.