BAL was performed in neonatal and adult mice as previously described 25 (link). For microbiology studies, BAL was performed aseptically and colony forming units (CFUs) enumerated were enumerated in serially plated dilutions [plated onto Columbia anaerobe sheep blood agar (Becton Dickinson, NJ) and incubated in a candle jar to facilitate the growth of microaerophilic bacteria at 37°C for 24 hours], as previously described 27 (link). Mouse TNFα, KC, MIP-2, LIX, IL-6, IgG1, IgG2a, IgG2b, IgG3, IgA, and IgM were measured in cell-free BAL using a Luminex-based assay (EMD Millipore, Billerica, MA), according to the manufacturer's instructions.