The migration of dendritic cell (DC)-enriched populations and alveolar macrophage (AM) populations isolated from PVG RT7.2 rats was studied after local administration to recipient PVG RT7.1 rats. The monoclonal antibody His41, which is directed against the common leukocyte antigen of the RT7.2 rat, was used to detect migrated cells. Injection of the splenic DC and AM subcutaneously into the footpads resulted in migration of both cell types to the popliteal lymph nodes after 24 h. DC located predominantly in the T cell-dependent areas, whereas AM located more in the medulla and medullary cords and spread throughout the outer cortex area. After intratracheal instillation of splenic DC, these cells were found predominantly in T cell-dependent areas of the draining lymph nodes of the lung after 24 h. In contrast, AM did not migrate to the draining lymph nodes after intratracheal instillation. Combined with those from earlier studies, these data show that DC present in the alveolar lumen may pick up airborne antigen and migrate to the draining lymph nodes of the lung, where they can induce primary T cell responses.