Dba 1j

C57BL/6J, DBA/1J, NOD, Mrp8-Cre, Cx3cr1-Cre, Lyz2-Cre, and Ubc-Cre^ERt2 mice were obtained from Jackson Laboratories. Elmo1^fl/fl and Elmo1^–/– mice have been described previously^{24 (link)}. To generate mice with deletion of Elmo1 in myeloid cells, neutrophils or macrophages, Elmo1^fl/fl mice were crossed to Lyz2-Cre, Mrp8-Cre or Cx3cr1-Cre mice, respectively. To generate mice with inducible deletion of Elmo1, Elmo1^fl/fl mice were crossed to Ubc-Cre^ERt2. In these mice, Elmo1 deletion was induced by three daily intraperitoneal injections of 40 mg/kg tamoxifen dissolved in corn oil. To generate Elmo1^–/–DBA mice, Elmo1^–/– mice were backcrossed onto the DBA/1J background for at least 5 generations. KRN TCR transgenic mice^{22 (link)} were a gift from Dr. Diane Mathis at the Harvard Medical School, and were bred to NOD mice to obtain the K/BxN mice^{23 (link)}, which develop progressive spontaneous arthritis. K/BxN serum was collected from 9-week old K/BxN mice by cardiac puncture. Age- and sex-matched littermate control animals were used for all experiments, and both males and females were assessed. In Elmo1^fl/flLyz2-Cre mice, reduced disease severity was observed in female, but not in male mice (data not shown). All animal procedures were approved by and performed according to guidelines of the Institutional Animal Care and Use Committee (IACUC) at the University of Virginia.