OPN KO mice are resistant to antibody-mediated TRALI, however, OPN administration restores PMN-dependent antibody-mediated TRALI. Lung W/D weight ratios (A) and percentage of pulmonary PMNs (B) in C57BL/6 OPN KO mice primed with LPS, depleted of CD4⁺ T cells, and injected with anti-MHC class I antibodies (clones 34-1-2s and AF6-88.5.5.3) and either PBS or OPN. For statistical analyses, only significant comparisons of interest are shown. Statistical analysis was performed with a 1-way analysis of variance (ANOVA) with a Tukey post hoc test. Each dot represents 1 mouse and error bars represent SD. *P < .05, ****P < .0001. NS, nonsignificant.