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. 2019 May 31;10:1030. doi: 10.3389/fimmu.2019.01030

Figure 2.

Figure 2

C3G autoantibodies of group 1 and group 2 influence C3 convertase assembly and dissociation by Factor H. (A) Two group 1 autoantibodies from patients #A and #J with high C3 convertase binding IgGs enhance C3-convertase formation. This enhancing effect is even stronger than the C3 convertase stabilizer and complement activator properdin. In contrast, group 2 autoantibodies from patients #a and# r do not enhance C3 convertase formation. Their effect is comparable to IgGs derived from NHS or from a DEAP-HUS patient with autoantibodies to Factor H or to buffer. (B) The same group1 antibodies when bound to the 3 convertase stabilize the enzyme and enhances resistance to factor H mediated dissociation. C3-convertase assembly in vitro and stabilization by autoantibodies are measured over 45 min by detection of convertase Bb using ELISA. (C) The same experiments as outlined in panel (A) are performed with all 33 patients derived autoantibody fractions and bound IgGs are identified after 45 min. All 12 group 1 antibodies enhance C3-convertase formation and again all group 2 antibodies have no or rather low effects (***p < 0.001). (D) All group 1 autoantibodies stabilize the C3 convertase from dissociation by factor H and all group 2 antibodies lack this activity (***p < 0.001).