Colliard S, et al. - Authors gauged the presence of anti–ficolin-2 antibodies in systemic lupus erythematosus (SLE) patients and assessed the relationship between the levels of these autoantibodies, clinical manifestations, and disease activity. The utility of anti–ficolin-2 as a complementary serologic biomarker for the diagnosis of active lupus with renal manifestations was supported in the findings. Compared to those with nonproliferative LN, significantly more positive anti–ficolin-2 antibodies were seen in patients with active proliferative LN. A very high specificity (98%) for the diagnosis of active LN was demonstrated with the combination of anti–ficolin-2, anti–ficolin-3, and anti-C1q.