Increased serum cortisol on oral food challenge in infants with food protein‐induced enterocolitis syndrome

Background An increase in absolute neutrophil count ( ANC ) is seen after oral food challenge test ( OFC ) in patients with food protein‐induced enterocolitis syndrome ( FPIES ). Although it has been suggested that interleukin ( IL )‐8 is involved in this phenomenon, a possible role for cortisol has not yet been studied. Methods Six positive OFC in five patients with FPIES due to cows’ milk ( CM ) proteins, and two negative OFC in two patients with suspected FPIES were analyzed. Absolute neutrophil count, serum IL ‐8, and serum cortisol were measured before OFC , 6 and 24 h after the ingestion of CM formula. Results For the positive OFC , ANC measured 6 h after the ingestion of CM formula was significantly higher than that measured before the OFC (median, 8,761 versus 2,297/μL; P < 0.05). Significant increases in serum cortisol and IL ‐8 were observed 6 h after OFC (cortisol, median 1,119 pg/ mL before versus 2,141 pg/ mL after, P < 0.05; IL ‐8, median 15.5 pg/ mL before versus 165.3 pg/ mL after, P < 0.05). The change ratio (i.e. ratio of that after OFC to that before OFC ) of ANC was significantly correlated not only with that of serum IL ‐8 ( r = 0.90, P < 0.01) but also with that of serum cortisol ( r = 0.76, P < 0.05). Moreover, the serum cortisol change ratio was significantly higher in subjects with vomiting than in those without (median, 2.5 versus 1.0, P < 0.05). Conclusions Serum cortisol, in combination with IL ‐8, affects the increase in ANC after OFC .