Contrary to the findings by Waters et al [4], our results suggested that S. maltophilia CF strains were more immunostimulatory than non-CF ones with regard to TNF-α - a potent proinflammatory cytokine that induces neutrophil and macrophage activation - and KC - a keratinocyte-derived chemoattractant for neutrophils. This evidence concerns the gene CALCA and cystic fibrosis.