MPO and acute respiratory distress syndrome: Immunohistochemistry (IHC) labelling of the common neutrophil markers lymphocyte antigen 6 complex locus G6D (Ly6G) and myeloperoxidase (MPO) (Fig. 2A and B) showed that, compared to control mice, VG-injected mice had slightly increased neutrophil recruitment in their lungs (Ly6G, 3.2% vs. 6.0%; MPO, 1.3% vs. 5.2%; both p < 0.05), while LPS-induced ALI mice had marked neutrophil accumulation in their lungs (Ly6G, 20.6%; MPO, 65.4%; both p < 0.05).