@article {Mehranijrheum.100650, author = {Taraneh Mehrani and Michelle Petri}, title = {IgM Anti-β2 Glycoprotein I Is Protective Against Lupus Nephritis and Renal Damage in Systemic Lupus Erythematosus}, elocation-id = {jrheum.100650}, year = {2010}, doi = {10.3899/jrheum.100650}, publisher = {The Journal of Rheumatology}, abstract = {Objective Antibodies to {\ss}2 glycoprotein I (IgG and IgM isotypes) have recently been added to the laboratory criteria of the revised antiphospholipid syndrome classification criteria. We investigated whether IgM anti-{\ss}2-glycoprotein I (anti-{\ss}2-GPI) is associated with clinical manifestations of systemic lupus erythematosus (SLE). Methods Anti-{\ss}2-GPI was measured in 796 patients with SLE (93\% women, 53\% white, 38\% African American, mean age 45 yrs). IgM anti-{\ss}2-GPI (\> 20 phospholipid units) was found in 16\%. Associations were determined with clinical manifestations of SLE and with components of the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index. Results As expected, IgM anti-{\ss}2-GPI was highly associated with both the lupus anticoagulant and with anticardiolipin. It was associated with transient ischemic attack (OR 2.64, p = 0.04), but not significantly with venous or arterial thrombosis. IgM anti-{\ss}2-GPI was protective against lupus nephritis (OR 0.54, p = 0.049), renal damage (p = 0.019), and hypertension (OR 0.58, p = 0.008). This protective effect remained after adjustment for ethnicity. Conclusion In SLE, IgM anti-{\ss}2-GPI is not associated with thrombosis but is protective against lupus nephritis and renal damage. {\textquotedblleft}Natural{\textquotedblright} autoantibodies of the IgM isotype may have a protective effect.}, issn = {0315-162X}, URL = {https://www.jrheum.org/content/early/2010/11/25/jrheum.100650}, eprint = {https://www.jrheum.org/content/early/2010/11/25/jrheum.100650.full.pdf}, journal = {The Journal of Rheumatology} }