CRP enhances antibody-mediated platelet destruction in vitro and in vivo. (A) Phagocytosis of pHrodo-labeled platelets opsonized with either isotype control or B2G1 antibody for 20 minutes at 37°C for CD16⁺ monocytes. (B) BALB/c mice developed thrombocytopenia 16 hours after intraperitoneal injection of the platelet- and megakaryocyte-specific rat anti-mouse CD41 IgG at 0.75 µg. Coinjection of 200 µg CRP with 0.75 µg rat anti-mouse CD41 IgG resulted in aggravated thrombocytopenia after 16 hours, whereas 200 µg CRP alone had no effect. Data are representative of 3 independent experiments; each data symbol represents 1 mouse (7 per group). Statistical comparisons were performed by 1-way ANOVA with Tukey’s posttest. *P ≤ .05; **P ≤ .01; ***P ≤ .001.