RT Journal Article SR Electronic T1 The XX sex chromosome complement in mice is associated with increased spontaneous lupus compared with XY JF Annals of the Rheumatic Diseases JO Ann Rheum Dis FD BMJ Publishing Group Ltd and European League Against Rheumatism SP 1418 OP 1422 DO 10.1136/annrheumdis-2011-201246 VO 71 IS 8 A1 Manda V Sasidhar A1 Noriko Itoh A1 Stefan M Gold A1 Gregory W Lawson A1 Rhonda R Voskuhl YR 2012 UL http://ard.bmj.com/content/71/8/1418.abstract AB Objectives Many autoimmune diseases are characterised by a female predominance. This may be caused by sex hormones, sex chromosomes or both. This report uses a transgenic mouse model to investigate how sex chromosome complement, not confounded by differences in gonadal type, might contribute to lupus pathogenesis. Methods Transgenic NZM2328 mice were created by deletion of the Sry gene from the Y chromosome, thereby separating genetic from gonadal sex. Survival, renal histopathology and markers of immune activation were compared in mice carrying the XX versus the XY− sex chromosome complement, with each genotype being ovary bearing. Results Mice with XX sex chromosome complement compared with XY− exhibited poorer survival rates and increased kidney pathology. Splenic T lymphocytes from XX mice demonstrated upregulated X-linked CD40 ligand expression and higher levels of activation markers ex vivo. Increased MMP, TGF and IL-13 production was found, while IL-2 was lower in XX mice. An accumulation of splenic follicular B cells and peritoneal marginal zone B cells was observed, coupled with upregulated costimulatory marker expression on B cells in XX mice. Conclusion These data show that the XX sex chromosome complement, compared with XY−, is associated with accelerated spontaneous lupus.