GL-2045 inhibition of CDC is completely dependent on the higher order multimer fractions. (A) GL-2045 was separated into 6 different fractions based on size by gel filtration. (B) SDS-PAGE of GL-2045 and fractions under nonreduced condition. (C) RTX-opsonized SUDHL4 cells were incubated with human complement serum pretreated with different fractions of GL-2045 at indicated concentrations. CDC activity was measured by Annexin V/7-AAD staining and analyzed by flow cytometry. The results are shown as the least squares mean ± SE estimated by ANCOVA. F, fractions.