The aim of this study was to compare in vitro release of eosinophil cationic protein (ECP) from peripheral blood eosinophils during active phases of childhood Crohn disease (CD) and ulcerative colitis with phases of remission. Ten children with CD and nine children with ulcerative colitis were investigated during 55 and 56 clinical visits, respectively. Each patient was investigated during at least one phase of clinically active disease and one phase of remission. Disease activity was assessed by means of the Paediatric Crohn Disease Activity Index (PCDAI) in Crohn disease and according to the clinical activity index of Rachmilewitz in ulcerative colitis. On an intra-individual basis, in vitro ECP release was significantly higher (P < 0.001) during active phases of CD and ulcerative colitis than in phases of remission (CD:median: 24.5 microg/l, range 16.0-61.2 versus median: 5.7 microg/l, range 2.0-16.7; ulcerative colitis: 14.8 microg/l, 8.3-39.8 versus 4.9 microg/l, 2.0-9.9). On an inte-individual basis, in CD and ulcerative colitis a strong and highly significant correlation was observed between disease activity indices and in vitro release of ECP from peripheral eosinophils (r = 0.89, P < 0.0001 and r = 0.82, P < 0.0001, respectively).
Conclusion: These results show that in vitro ECP release from peripheral eosinophils reflects disease activity in both CD and ulcerative colitis and therefore can be used as a new appropriate laboratory parameter for assessment of disease activity in chronic inflammatory bowel disease.