In this study we report the characterization of a population of lung resident CD11b⁻CD11c⁺ cells that are able to take up inhaled antigen and retain it for extended periods of time. Ovalbumin conjugated to fluorescein-isothiocyanate (FITC-OVA) administered intranasally to mice was taken up by two main populations of cells in the lung, a migratory CD11c⁺CD11b⁺ population consisting of dendritic cells (DC), which rapidly transported antigen to the draining lymph node (LN), and a resident CD11b⁻CD11c⁺ population that retained engulfed antigen without apparently degrading it for up to 8 wk after administration. The FITC⁺CD11b⁻CD11c⁺ cells did not migrate to draining LN at a detectable rate, and did not up-regulate expression of costimulatory molecules in response to LPS treatment. FITC⁺CD11b⁻CD11c⁺ cells were found in the lung and bronchoalveolar lavage fluid, and their distribution was compatible with macrophages. Although FITC⁺CD11b⁻CD11c⁺ cells expressed the DC marker DEC205 and other molecules associated with antigen-presenting cell function, they did not induce proliferation of antigen-specific CD4⁺ T cells in vitro or acute cytokine production by activated CD4⁺ T cells in vivo. Thus, FITC⁺CD11b⁻CD11c⁺ cells appear to represent an intermediate cell type sharing properties with DC and macrophages. These cells may have a role in modulating the responses of lung resident T cells to inhaled antigens.