Transient autoimmunity was induced in female C57BL/6 and actin-resistant, salt-resistant and hyperactive mutant of DNase I (ash.DNase I) mice by intraperitoneal injection with a single dose of 100 μg lipopolysaccharide (LPS; E. coli 0111:B4). Serum and plasma samples were collected from mice before, and 9 hours, 7 days and 14 days post-LPS injection. (a) Plasma DNA concentration was determined by fluorometric assay with the dye PicoGreen, as described in the Materials and methods. Assays were performed in triplicate and values represent the mean results from each mouse. (b) Levels of serum IgM anti-ssDNA antibodies in mice before and 7 days and 14 days post-injection of LPS. Values are expressed in arbitrary ELISA units (AEU) related to a standard positive sample that was assigned a value of 100 AEU. (c) The level of IgM deposited in the glomeruli was quantified by immunofluorescence and expressed as arbitrary fluorescence units (AFU). The data are representative of four separate experiments.