Aims: The main aim of this study is to access the predictive value of Treg and Breg for the clinical effect of Infliximab in the treatment through analyzing the relationship between Breg and Treg and the efficacy of Infliximab.||Design: It is a prospective, observational study. In the treatment group, 32 patients with Crohn's disease (CD) about to start Infliximab-treatment are recruited. They have blood samples drawn at week 0 and 14 of Infliximab treatment. 33 healthy individuals serve as a control group. Controls are only investigated once. All treatment and follow-up are according to national guidelines. The frequencies of Treg and Breg are investigated using flow cytometry. Subjects data are extracted from various registries.