Experimental protocol for the study.

Mice were sensitized by i.p. administration of 2 µg ovalbumin admixed with 100 µl alum at day 0 and 14. At day 21, the mice were treated by i.n. administration (50 µl volume) of PBS, live A. baumannii (∼10⁸ CFU) or formalin-fixed (ff) A. baumannii (∼10⁸ CFU). At day 28, mice were intranasally challenged with 100 µg OVA in 50 µl PBS or 50 µl PBS alone, as described in Material and Methods. Five days after challenge (day 33), mice were sacrificed for sample collection.