On localization of inhaled antigens in late asthmatic response in an animal model

To clarify the initiation of late asthmatic response (LAR), the localization and fate of inhaled antigens were studied using an animal model of LAR. Guinea pigs were sensitized by ascaris suum and aluminum gel. Radioiodinated ascaris suum and ovalbumin as control were subsequently injected into the trachea of the guinea pig to determine the radioactivity of bronchoalveolar lavege (BAL) cells and fluid (BALF) components before and after LAR. The localization of antigens was also examined by autoradiography of BAL cells and lung tissue sections. The radioactivity of radioiodinated ascaris in BAL cells and lung tissue increased during LAR with increases in macrophages and neutrophils, although in non-responding animals inhaled antigens gradualy disappeared from the airway. The radioactivity of radioiodinated ovalbumin gradually decreased regardless of LAR. Autoradiographic study showed that the inhaled antigens were located in the cytoplasm of alveolar macrophages in BALF and lung tissue. These data indicate that inhaled antigens may accumulate and migrate with numerous inflammatory cells such as macrophages and neutrophils in late phase bronchial response.