Gil-Borras R, et al. - Experts intended to assess the frequency of B1a cells (CD19+CD5+) in the peripheral blood of patients with Crohn’s disease (CD) and its association with disease severity. Among CD patients, the B1a cell count in peripheral blood was lower. The severity of the disease (penetrating or perforating, Simple Endoscopy Score and surgery complication) was directly related to this decrease. Findings indicated that B1a cells played an important role in immune protection in CD.