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Herein, we investigated the effect of bacterial lipooligosaccharides (LOS), from <i>Acinetobacter baumannii</i>, on the expression of pro-inflammatory genes that play an essential role in bacterial clearance. LAD2 human mast cells were stimulated with LOS derived from two strains of <i>A. baumannii</i>—ATCC 19606 and MDRA T14. LOS exposure induced the expression of genes for pro-inflammatory mediators, including TNF-α, IL-8, LTC4S, CCL4, and TLR4. The mRNA expression levels of a majority of the pro-inflammatory genes, except TLR4, in <i>A. baumannii</i>-LOS stimulated mast cells were increased. Moreover, co-culture of neutrophils with the supernatant obtained from LOS (ATCC 19606 and MDRA T14)-induced LAD2 cells increased the transmigration of neutrophils, which plays a critical role in the early protection against bacterial infections. The results of the present study suggest that LOS could be involved in the pathogenicity of <i>A. baumannii</i> by inducing inflammatory responses via mast cells and that IL-8 is involved in recruiting neutrophils in response to bacterial invasion.