Fig. 1.

Development of a novel assay for the detection of circulating immune complexes. a Levels of FcγRIIA on neutrophils upon addition of heat-aggregated IgG (IC) as determined by binding of FcγRIIA antibody clones IV.3 (red) and FUN-2 (black). b Correlation plot for IV.3 and FUN-2. c, d Levels of ICs in healthy individuals (HC) and patients with SLE at the time point of low and high disease activity as measured by c IV.3 and d commercial assay. e Correlation plot for the two IC assays. Statistical analyses were performed using the Mann-Whitney U test and Spearman’s correlation with *p < 0.05,**p < 0.01, and ***p < 0.001