Accessory cells with immunophenotypic and functional features of monocyte-derived dendritic cells are recruited to the lung during pulmonary inflammation

Pulmonary macrophages (M phi) increase in tissue and bronchoalveolar lavage (BAL) fluid during inflammation caused by bleomycin (BLM). This study demo nstrates that increasing numbers of exudate M phi in BLM lung injury exhibi t dendritic cell(DC) features. After the intratracheal administration of BL M (0.075 U), adherent mononuclear cells front the bronchoalveolar lavage fl uid (BAMC) of C57BL/6 mice were characterized for morphology, immunophenoty pe, and accessory cell activities. At day 7 post-BLM, 48% of CD11b(+) BAMC displayed features of DC differentiation, as judged by dendritic morphology , expression of class II MHC, 33D1, Factor XIIIa, CD80, and CD86 antigens, and the ability to support a primary allogeneic lymphocyte response (MLR). After BLM treatment, CD11b(+) peripheral blood monocytes also showed increa sed expression of 33D1, Factor XIIIa, CD86? and the ability to stimulate an MLR. We conclude that inflammatory DC with immunophenotypic features of mo nocyte-derived DC increase in the peripheral blood and lung after an inflam matory stimulus.