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Elevation of Serum IL-17 Levels was Demonstrated after Oral Food Challenge in Infants with Food Protein-Induced Enterocolitis Syndrome

      RATIONALE: Food protein-induced enterocolitis syndrome (FPIES) is characterized by cell-mediated immune responses with elevated neutrophil counts, however, no data have been available regarding the role of IL-17 in the pathogenesis of FPIES. We present here two infants fulfilling FPIES criteria who demonstrated elevated serum IL-17 levels after oral food challenge (OFC).
      METHODS: Two boys with trisomy 21 developed vomiting and diarrhea at least 2 hours after ingestion of milk at the age of 2 and 4 months, respectively. Open OFC tests were undertaken at 8 month-old and 2 year old after informed consent was obtained. Blood samples were serially collected before and up to 24 hours after OFC. PBMC from each patient were incubated with LPS-depleted cow's milk proteins and the culture supernatants were harvested at 6 and 24 hours after culture. The concentrations of various cytokines were measured by ELISA and CBA.
      RESULTS: The patients developed recurrent vomiting, fever and lethargy within 2 hours and watery diarrhea 6 hours after OFC. Peripheral blood neutrophil counts were also elevated. Significantly elevated serum IL-17A levels (74 and 324 pg/mL) and IL-6 levels were observed in each patient at one and two hours after OFC. However, IL-17A was undetectable in the culture supernatants of PBMC after antigen stimulation.
      CONCLUSIONS: Our study suggests that in a certain subtype of patients with FPIES, IL-17 is secreted in a very early stage and is likely to be involved in the recruitment of neutorphils, whereas the source(s) of IL-17 remains to be clarified.