抄録
Neurotrophins are growth factors that exert multiple actions on neuronal and nonneuronal cells. We have previously shown that neurotrophins, NT-3 and NT-4/5, are expressed in mouse alveolar macrophages. In the present study, we further attempted to clarify the intracellular localization of NT-3 and its co-localization with interleukin IL-1, fibroblast growth factor FGF, and histamine in alveolar macrophages. Immunocytochemical staining with antibodies against NT-3, lysosomal membrane protein LAMP-2, IL-1, FGF, and histamine was performed on alveolar and peritoneal macrophages obtained from the adult mouse. Approximately 80% of alveolar macrophages were immunoreactive for NT-3. In contrast, peritoneal macrophages were rarely immunoreactive for NT-3 (<5%). In these NT-3-immunoreactive macrophages, NT-3 was localized in intracellular granules. The granule localization of NT-3 was confirmed, since the NT-3-containing granules were immunoreactive for LAMP-2, which labels intracellular granule membrane. Almost all alveolar and peritoneal macrophages were immunoreactive for IL-1, FGF, and histamine. IL-1 and FGF were diffusely distributed in the cytoplasm. Histamine was localized in granules. In some granules, histamine was co-localized with NT-3. Since a large number of alveolar macrophages contain NT-3 in their granules and NT-3 is co-localized with histamine in some granules, they may be co-released in an exocytotic manner from alveolar macrophages and may play synergic roles in pulmonary pathophysiology. [J Physiol Sci. 2006;56 Suppl:S120]
