Reproduction of TRALI in an ex vivo rat lung model after depletion of rat neutrophils. To exclude a possible contribution of rat neutrophils adherent to the pulmonary vasculature, rats were depleted from neutrophils 24 hours before LPS injection and subsequent lung explantation. (A) Differential blood counts obtained before (left) and after (right) neutrophil depletion; N indicates neutrophils; Ly, lymphocytes; Mo, monocytes. Results are given as mean values ± SDs. P < .01 for neutrophils before and after depletion (n = 6). (B) As in previous experiments (Figure 4B), lungs were perfused with human neutrophils and supernatant from human monocyte cultures incubated with matched or unmatched human HLA class II antibodies. A significant increase in endothelial permeability (K_fc) and lung weight is observed after 35 minutes in the presence of matched monocyte supernatant (P < .01; n = 3). (C) As in previous experiments (Figure 5A), lungs were perfused with human neutrophils, HLA class II antibodies, and monocytes that bear or do not bear the cognate HLA class II antigen. A significant increase in K_fc and lung weight after 35 minutes and severe edema after 70 minutes is observed in the presence of monocytes that bear the cognate antigen (P < .01; n = 3).