Sensitization by intratracheally injected dendritic cells is independent of antigen presentation by host antigen-presenting cells.

Adoptive transfer of antigen-pulsed dendritic cells (DC) in the airways of mice has been used as a model system for eosinophilic airway inflammation, which allows studying the DC-specific contribution of genes of interest or reagents to induced inflammation by genetically modifying DC or exposure of DC to compounds prior to injection in the airways. Antigen transfer and CD4+ T cell priming by endogenous antigen-presenting cells (APCs) may interfere with the correct interpretation of the data obtained in this model, however. We therefore examined antigen transfer and indirect CD4+ T cell priming by host APCs in this model system. Transfer of antigen between injected DC and host cells appeared to be minimal but could not be totally excluded. However, only direct antigen presentation by injected DC resulted in robust CD4+ T cell priming and eosinophilic airway inflammation. Thus, this adoptive transfer model is well suited to study the role of DC in eosinophilic airway inflammation.