Figure 4.

Effect of Lufaxin on factor D activity and on the direct binding of complement components. (A) Effect of Lufaxin on factor D activity. Purified factor D (+D) was mixed with specific substrate Z-1-Lys-SBzL in the presence or absence of Lufaxin and incubated at 37°C. Tubes without factor D (−D) were used as controls. Different letters indicate statistical difference between groups (p < 0.05). (B) ELISA plates were sensitized with 0.5 µM of purified properdin, C3b, factor B, Bb, factor D, or 1% BSA followed by incubation with 120 nM of Lufaxin. Mouse anti-Lufaxin serum was used to detect significant binding. Asterisk indicates statistical difference (p < 0.01) from controls (BSA). (C) Different concentrations of Lufaxin were carried on AP-hemolytic assays using properdin depleted serum.