CD71 erythroid suppressor cells impair adaptive immunity against Bordetella pertussis.

Infant's immune system cannot control infection or respond to vaccination as efficiently as older individuals, a phenomenon that has been attributed to immunological immaturity. Recently, we challenged this notion and proposed the presence of actively immunosuppressive and physiologically enriched CD71 erythroid cells in neonates. Here we utilized Bordetella pertussis, a common neonatal respiratory tract pathogen, as a proof of concept to investigate the role of these cells in adaptive immunity. We observed that CD71 cells have distinctive immunosuppressive properties and prevent recruitment of immune cells to the mucosal site of infection. CD71 cells ablation unleashed induction of B. pertussis-specific protective cytokines (IL-17 and IFN-γ) in the lungs and spleen upon re-infection or vaccination. We also found that CD71 cells suppress systemic and mucosal B. pertussis-specific antibody responses. Enhanced antigen-specific adaptive immunity following CD71 cells depletion increased resistance of mice to B. pertussis infection. Furthermore, we found that human cord blood CD71 cells also suppress T and B cell functions in vitro. Collectively, these data provide important insight into the role of CD71 erythroid cells in adaptive immunity. We anticipate our results will spark renewed investigation in modulating the function of these cells to enhance host defense to infections in newborns.