Monocytes/macrophages are required in WT mice but only accessory in CD32A⁺ mice for the initiation of antibody-mediated TRALI. (A) The Gr-1 mAb RB6-8C5 or control rIgG2bk (0.5 mg/kg, intravenous [IV]) 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, IV) or vehicle into CD32A⁺ (n = 3-16) or CD32A^– (n = 3-16) mice. (B) Clodronate liposomes (2 mL/kg, IV), or vehicle, were injected 6 hours before hIgG1-34-1-2S challenge (1.5 mg/kg, IV) into LPS-sensitized (0.1 mg/kg, intraperitoneal) CD32A^– or CD32A⁺ mice. Protein concentrations in BALs were evaluated 15 minutes later (CD32A^–, n = 7-12; CD32A⁺, n = 4-13). Results are presented as the mean ± standard error of the mean. P > .05 (not significant [ns]), *P < .05, ***P < .001 by one-way analysis of variance.