(A) Immunoprecipitation of suPAR by plasma IgG.¹²⁵I-suPAR or ¹²⁵I-plasminogen (final concentration 50 nmol/L) was added to 0.5 mL native plasma [black bars: (+)] or to IgG-depleted plasma [open bars: (−)]. The mixture was incubated with protein G-Agarose, centrifuged, and washed repeatedly with PBS, and the precipitated radioactivity was measured. The mean ± SEM of three experiments is shown. (B) Immunoprecipitation of suPAR by purified IgG. Protein G-Agarose (0.5 mL) was added to a mixture containing either 50 nmol/L ¹²⁵I-suPAR or 50 nmol/L¹²⁵I-plasminogen plus 1 mg/mL IgG (black bars) or 1 mg/mL BSA (open bars), and the precipitated radioactivity was measured as above. The mean ± SEM of three experiments is shown.