MPO and cystic fibrosis: This effect may be of particular relevance – even though not specifically related – in cystic fibrosis, where eosinophils as well as neutrophils have been suggested to have an increased propensity to release their granule proteins (ECP and MPO), due to still unknown priming mechanisms (e.g. cytokines stimulation or upregulation of CR3-receptors) [36].