Immunologic aspects of lung diseases and cystic fibrosis
P. A. Greenberger
Immunologic lung disorders are accompanied by an array of laboratory
abnormalities, some of which contribute to disease pathogenesis. Allergic
bronchopulmonary aspergillosis, which complicates asthma and cystic
fibrosis, causes mucous plugging of airways, eosinophilic pneumonia, and
bronchiolitis obliterans. Aspergillus fumigatus, growing saprophytically in
bronchial mucus, is responsible for most cases, and prednisone, not
antifungal agents, is the drug of choice because it controls the
immunologic responses of the lung. In cystic fibrosis, epithelial surface
fluid from the lung does not kill Pseudomonas aeruginosa, in part because
antibodies to P aeruginosa are plentiful but ineffective in opsonizing
bacteria. Neutrophil-derived elastase cleaves immunoglobulins and digests
the C3b receptor on neutrophils, which limits phagocytosis of pathogens. In
helminth infections and infestations, pulmonary and peripheral blood
eosinophilia can be accompanied by increases in total and antiparasite IgE
concentrations and generate T(H)2 CD4+ T-lymphocyte responses.
Understanding the immunologic abnormalities of lung disorders may lead to
more effective therapies.
