Figure 1.

Quantification of the kallikrein/kinin proteins FXII, prekallikrein and high molecular weight kininogen (HK). The kallikrein/kinin system was activated as reflected in high consumption of FXII, prekallikrein, and HK. EDTA plasma from COVID-19 patients and controls were analyzed by capillary electrophoresis under reduced SDS-PAGE-like conditions and the specific kallikrein/kinin proteins detected by specific antibodies against FXII, prekallikrein, and HK, respectively (A, D, H). The area under the curves of the scan of the chemiluminescence intensities plotted in the panels (B, E, I) were interpreted to their specific concentration by comparing the value for each peak with a standard curve specific for each protein (C, F, J). The concentration of KK-C1INH complexes were analyzed by sandwich ELISA (panel G). Representative patients and controls are shown in panels (A, B, D, E, H, I). The Mann-Whitney U test was used to calculate differences between the groups. For more details see Materials and Methods. pp, plasma pool; KK, kallikrein; C1INH, C1inhibitor; HK, high molecular weight kininogen.