Broncho‐alveolar leucocyte responses during primary and secondary Nippostrongylus brasiliensis infection in the rat

Using broncho-alveolar lavage, we have studied the cellular responses in the rat lung following primary and secondary infection with Nippostrongylus brasiliensis. During the primary infection, there was a biphasic increase in total broncho-alveolar leucocytes and in the absolute numbers of macrophages, neutrophils, eosinophils and lymphocytes. The first peak occurred on days 4-6, and the second peak occurred around day 16, after infection. During the secondary infection there was an anamnestic-like response by all cell types. These data suggest that the broncho-alveolar leucocyte responses to infection have an immunological basis and that in addition to the alveolar macrophage, neutrophils, eosinophils and lymphocytes may play a significant role in lung resistance against migrating helminth larvae.