Supplementary Material for: High Titer Anti-Basement Membrane Antibodies in a Subset of Patients with Pediatric Systemic Lupus Erythematosus Orjuela A. Suwanichkul A. Canter D. Minard C.G. Devaraj S. Hicks M.J. Muscal E. Wenderfer S.E. 10.6084/m9.figshare.5127976.v1 https://karger.figshare.com/articles/dataset/Supplementary_Material_for_High_Titer_Anti-Basement_Membrane_Antibodies_in_a_Subset_of_Patients_with_Pediatric_Systemic_Lupus_Erythematosus/5127976 <b><i>Background/Aims:</i></b> There is a critical need for more noninvasive biomarkers to identify nephritis in patients with systemic lupus erythematosus (SLE). Recent studies in a model mouse and an adult SLE patient cohort suggest that anti-basement membrane antibody levels correlate well with lupus activity and kidney injury. The purpose of this study was to assess the anti-basement membrane reactivity in pediatric SLE (pSLE) patients with or without nephritis. <b><i>Methods:</i></b> Auto-antibodies to basement membrane antigens were assessed using an anti-matrigel ELISA. Endpoint titers were measured in pSLE patients and healthy children, as well as in autoimmune and non-immune mice, with good reproducing capabilities. Findings were also analyzed with respect to the presence or absence of nephritis, dsDNA antibodies, and other manifestations of pSLE. <b><i>Results:</i></b> MRL/lpr mice developed high-titer anti-matrigel antibodies, whereas C57BL/6 mice did not. In a cohort of 21 pSLE patients and 22 pediatric controls, high-titer anti-matrigel IgG, IgM and IgA antibody levels were specific for pSLE. High-titer anti-matrigel IgG3 levels could distinguish with good sensitivity the 13 pSLE patients with a history of nephritis from the 8 non-renal pSLE patients. High-titer anti-matrigel IgG, IgA, IgM or IgG3 did not correlate with positive anti-double stranded DNA, but defined an overlapping subset of patients. <b><i>Conclusion:</i></b> The addition of anti-basement membrane antibody testing to serologic testing in pSLE may help to monitor disease activity or to define important subsets of patients with risks for specific disease manifestations. 2015-04-25 00:00:00 Glomerulonephritis Pediatrics Inflammation