5C12 anti-FXII antibody treatment decreases complement activation after challenge with a lethal dose of HI-SA (LDSA). (A-C) Time course dynamics of plasma levels of nucleosomes, a cell death marker (A), and of complement activation markers C3b (B) and soluble C5b-9 (C). Same time points are compared between the control baboons (LDSA) and the 5C12-treated animals (LDSA + 5C12) using the generalized least squares (gls) function. *P < .05; **P < .01; ***P < .001. The overall P value (pvl) describing the difference between the 2 curves is shown on each graph. P < .05 is considered significant. (D) Immunofluorescence staining of C5b-9 terminal complement complex (red) in kidneys of baboons challenged with LDSA, without (left) or with 5C12 treatment (LDSA + 5C12; right). Nuclei were stained with To-PRO-3 (blue). Scale bars, 100 µm. Confocal images were captured by using a Nikon Eclipse TE2000-U microscope equipped with a Nikon C1 scanning head; the Nikon EZ-C1 software (version 3.80) was used for image acquisition.