Pretreatment with 3G3 antibody prevented tissue damage and complement activation following a lethal dose of heat-inactivated S aureus injection in baboons. Time course changes of plasma levels of cell death markers, nucleosomes (A) and lactate dehydrogenase (B), and of complement activation markers C3b (C) and soluble C5b-9 (D). Data are presented as mean ± SEM. Same time point data are compared between untreated (LDSA) and 3G3-pretreated (LDSA + 3G3) animals using 2-tailed Student t test: *P < .05, **P < .01, ***P < .001. (E) Immunofluorescence staining of C5b-9 terminal complement complex (green) in the kidney of S aureus–challenged animals without (LDSA; left) or with 3G3 pretreatment (LDSA + 3G3; right). Note stronger C5b-9 staining in the T and G of nontreated vs treated baboons. Confocal images were captured on a Nikon Eclipse TE2000-U inverted microscope equipped with a Nikon C1 scanning head. Images were acquired and processed using EZ-C1 software (v 3.80; Nikon). Scale bars, 100 µm. G, glomeruli; T, tubule.