Role of ROIs and NO in basal and LT-enhanced AM microbicidal activity. (A) Rat AMs were pretreated with the NADPH oxidase inhibitor DPI (10 μM) for 20 minutes before the addition of opsonized K pneumoniae. Thirty minutes later, DPI was added back with or without LTB₄ (1 nM), LTC₄ plus LTD₄ (100 nM each, cysLTs), or LT mixture (LTB₄, 1 nm; LTC₄ and LTD₄, 100 nM each). (B) AMs from WT or gp91phox KO mice were infected, and LT mixture was added 30 minutes after infection. □ indicates control; ▪, LTs. (C) Rat AMs were pretreated with the NO synthase inhibitor L-NAME (1 mM) for 20 minutes before the addition of opsonized K pneumoniae. Thirty minutes later L-NAME was added back with or without LTB₄ (1 nM), LTC₄ plus LTD₄ (100 nM each, cysLTs), or LT mixture (LTB₄, 1 nm; LTC₄ and LTD₄, 100 nM each). Microbicidal activity was assessed colorimetrically. Data are expressed as the mean ± SE percentage of survival of ingested bacteria from quadruplicate values from 1 of 2 representative experiments. ^*P < .05 versus control. #P < .05 versus L-NAME group by ANOVA.