Lung immunology and its contribution to the immunopathogenesis of certain respiratory diseases

Abstract

For many years allergic and hypersensitivity mechanisms have been implicated in the cause of asthma, drug-induced lung diseases, and certain occupational inhalant disorders, comprising a limited group of presumably immunologic lung diseases. Except for antigen-specific asthma (extrinsic form), little was known about actual immunopathogenetic pathways involved. Systemic collagen-vascular diseases were known to involve the lungs, but in a secondary way, as part of a multiorgan disease. However, in the past 20 years, this limited perception of immunologic lung diseases has expanded dramatically, coincident with the spectacular development of new techniques to study humoral (antibody) and cellular immunity and inflammatory cells. Now, most lung disorders that affect the conducting airways, air exchange surface, and the architectural supporting structure of the alveoli, known as the interstitium, are perceived to involve immune mechanisms in some way. The designation “immunologic” may lead to some confusion in the description of certain lung diseases because the term immunologic often has a dual meaning. In the broadest sense, if a disease produces some evidence of adaptive immunity in the affected host through formation of specific antibodies, autoantibodies, or cellular responses, it is by definition immunologic. If the methods used to study the patient, whether to establish a diagnosis or as part of research investigation, use immunologic techniques