Respiratory syncytial virus replication induces Indoleamine 2,3-dioxygenase (IDO) activation in human dendritic cells

Objective/purpose Induction of IDO in dendritic cells (DCs) depletes the essential amino acid, tryptophan, and generates a family of catabolites known as kynurenines (KYN). IDO activity is reported to have immunomodulatory effects, including the selective induction of apoptosis in T-helper 1 (Th1) lymphocytes, an effect not seen with Th2 cells that are dominant in allergic asthma. Infants hospitalized for RSV-related bronchiolitis have increased risk of developing asthma (48% vs. 8% in control). Induction of IDO activity by RSV may explain the link between RSV bronchiolitis and asthma pathogenesis. IDO is induced by various cytokines and a number of non-airway viruses; however, RSV has not yet been studied. We hypothesize that RSV induce IDO activation in human dendritic cells (DCs).