MPO and eosinophilic gastroenteritis: The unexpected rise in the fluorescent signal of dapsone-treated samples could indicate that in these assay conditions, dapsone acted as a radical shuttle and improved the oxidation of AmplexUltraRed by myeloperoxidase.31 Possible sources of non-myeloperoxidase peroxidase contamination in this assay could be further investigated by assessing the performance of this assay in individuals with eosinophilic enteritis.