Which of the following statements concerning alveolar macrophages is true?
Alveolar macrophages secrete elastase. Normally, a1-antitrypsin, a serum protein, interacts with elastase, thereby protecting the lung against damage that may lead to emphysema.
They secrete a1-antitrypsin.
They secrete elastase.
They originate from blood neutrophils
They may play a role in causing hyaline membrane disease
Systemic histology