Platelets are required for the FcγRIIA/CD32A–induced aggravation of antibody-mediated TRALI. The mAb R300 or control rIgG2a (0.5 mg/kg, intravenous) was administered 24 hours before LPS (0.1 mg/kg, intraperitoneal) and protein concentrations in BALs were analyzed 15 minutes after injection of the mAb hIgG1-34-1-2S (1.5 mg/kg, intravenous) or vehicle into CD32A^– or CD32A⁺ mice (n ≥ 9). Results are presented as the mean ± standard error of the mean. P > .05 (not significant [ns]), *P < .05, **P < .01, ***P < .001 by one-way analysis of variance.