Fig 1: Spike recovery assays. (A) Known concentrations of recombinant human IL-18, CXCL9, CXCL10, S100A8/9, and S100A12 were added to human AB serum, and 12 serial dilutions were performed. Data for CXCL10 and S100 proteins can be found in the Supplement. (B) Representative schema of the spike recovery assays, including participating centers and their respective measurement platforms. Not all biomarkers were tested at every site. (C) Correlation plot of spiked recombinant IL-18 concentration vs. measured IL-18 values from each platform. (D) Percent recovery of spiked recombinant IL-18 at each concentration from each participating center. (E) Correlation plot of spiked recombinant CXCL9 concentration vs. measured CXCL9 values from each platform. (F) Percent recovery of spiked recombinant CXCL9 at each concentration from each center