Figure 5

Competitive binding of patients' and controls' purified IgG (pIgG). Patients' pIgG showed a significantly greater affinity than controls for target organ epitopes. Representative image of double immunostaining of consecutive control artery sections with different concentrations of antibodies from one patient and a matched control (top). Antibody binding was quantified by fluorescence intensity and densitometric computer-assisted analysis. Percentage of binding to sections for patients (red, n = 20) and controls (blue, n = 20) are displayed according to the ratio of the concentration of IgG from the patient to the concentration of IgG from the control. Dotted line = equal concentration for patients' and controls' IgG (p < 0.001 patients vs controls).