Four known APA-positive and one known APA-negative plasma samples were assessed by indirect ELISA against Adagen-coated plates for detecting bound IgG (right axis; solid black bars), and also by surface fluoroimmunoassay toward EG2-OMe, EG3-OMe, and EG5-OMe bottlebrush surfaces (left axis; empty, striped, and checkered bars, respectively). Results are shown as mean ± s.d. (n = 5 replicates for ELISA, n = 4 replicates for EG2-OMe and EG5-OMe, and n = 2 for EG3-OMe).