Blockade of the 5-HT2A serotonin receptor prevents the exacerbation of antibody-mediated TRALI in CD32A⁺ mice. (A) The selective 5-HT2A serotonin receptor antagonist sarpogrelate (1 mg/kg, intravenous [IV]) or saline was administered 5 minutes before hIgG1-34-1-2S challenge (1.5 mg/kg, IV) in LPS-sensitized (0.1 mg/kg, intraperitoneal [IP]) CD32A^– or CD32A⁺ mice. Protein concentrations in BALs were evaluated 15 minutes later (n = 6). (B) Pulmonary elastance (Ers) in LPS-sensitized (0.1 mg/kg, IP) CD32A^– or CD32A⁺ mice after injection of the mAb hIgG1-34-1-2S (0.75 mg/kg, IV, n = 4) or vehicle (n = 3). (C) Sarpogrelate (1 mg/kg, IV) or saline was administered 5 minutes after hIgG1-34-1-2S challenge (1.5 mg/kg, IV) in LPS-sensitized (0.1 mg/kg, IP) CD32A^– or CD32A⁺ mice. Protein concentrations in BALs were evaluated 15 minutes later (n ≥ 22). Results are presented as the mean ± standard error of the mean. P > .05 (not significant [ns]), **P < .01 by one-way analysis of variance (panels A and C).