Figure 4

Competitive binding of properdin (P) and factor H (fH) on proximal tubular epithelial cells (PTECs). PTECs were incubated with variable concentrations of a mixture of P and fH for 3 h. (a) In the mixture of P and fH (P concentration, 5 μg/mL; fH concentration, 0–400 μg/mL), the depositions of fH were increased in a dose-dependent manner, while those of P remained unchanged, as observed by IF. (b) In the mixture of P and fH (fH concentration, 20 μg/mL; P, 0–10 μg/mL), the depositions of P were increased in a dose-dependent manner, while those of fH remained unchanged. Original magnification: ×100. Arrow: depositions of P or fH.