An animal model of hypersensitivity pneumonitis in rabbits. Development of chronic pulmonary inflammation and cell-mediated hypersensitivity after repeated aerosol challenge

Chronic pulmonary inflammation was produced in immunized rabbits by repeated aerosol exposure to soluble antigen. The pulmonary inflammatory response was correlated with the development of cell-mediated hypersensitivity in the lung as evaluated by migration-inhibition studies using bronchoalveolar cells. Such inflammation could be produced with either pigeon dropping extract, an etiologic agent of hypersensitivity pneumonitis, or with human gamma globulin. Development of the inflammatory response was immunospecific and could not be transferred to normal recipients with large quantities of immune serum. Collectively, these data suggest that the development of pulmonary inflammation was due to a cell-mediated immunologic reaction in the lung.

Humidifier-associated extrinsic allergic alveolitis

Three cases of allergic alveolitis due to indoor humdification systems are described. Thermoactinomyces vulgaris precipitins were detected in the serum of a 37-year-old female patient who had typical febrile attacks during exposure to cool-mist from a home humidifier. When the cause was detected and eliminated, the symptoms and signs disappeared and the woman's gas transfer factor improved from 56% to normal within six months. In a printing office a 60-year-old woman had had febrile attacks with cough for more than a year. The patient herself associated the respiratory disease with a cool-mist humidifier sometimes used at work. The water reservoir was heavily contaminated with amoebas (Amoeba proteus), which might have been the causative organisms in this case. Aspergillus fumigatus precipitins were found in the serum of a 53-year-old female printer with the clinical picture of occupational allergic alveolitis. The same organism was detected in the ambient air of the printing office.

Asthma and extrinsic allergic alveolitis due to Merulius lacrymans

A teacher with breathlessness of insidious onset developed acute symptoms on return home following his discharge from hospital. His flat was found to have extensive dry rot (Merulius lacrymans). Precipitins and specific IgE and IgG antibody against M. lacrymans were present and intracutaneous testing gave a typical dual skin reaction. Pulmonary physiology demonstrated airflow obstruction with a low DLCO and KCO, and a chest X-ray showed diffuse micronodular shadowing, maximal in the mid-zones. Inhalation challenge testing provoked a combined asthmatic reaction without a change in DLCO. Rapid clinical recovery and more gradual radiographic and physiological improvement followed cessation of exposure to the antigen.

Environmental injury of the lung: role of humoral mediators

Environmental lung injury may take the form of acute tracheobronchitis, asthma, pulmonary edema, chronic bronchitis, emphysema, allergic pneumonitis, fibrosing alveolitis, pleurisy, and neoplastic disease. Environmental factors eliciting these responses include irritant gases and fumes, oxidants, organic allergens, inorganic dust, bacterial enzymes, and high partial pressures of oxygen. The basic pulmonary reactions to these toxic agents--bronchoconstriction, vasoconstriction, increased vascular permeability, inflammation, carcinogenesis--may be mediated, aggravated, or modulated by biologically active substances. These humoral agents include biogenic amines (e.g. histamine): peptides (e.g., bradykinin, vasoactive intestinal peptide, and spasmogenic lung peptide); enzymes (e.g., proteases, superoxide dismutase, and mixed function oxidases); and acidic lipids (e.g., prostaglandins, prostaglandin endoperoxides, and thromboxanes).

Antibody activity in sera of patients with humidifier disease: studies of the water supply as a source of antigens

In 5 patients with respiratory symptoms consistent with humidifier or air conditioner disease, a hypersensitivity pneumonitis, no identifiable organism was cultured from the humidifier water (HW). The water source to the humidifier or air conditioner was investigated for possible antigens which might explain the occurrence of the disease. Three subjects who lived in the same city supplied by Lake Michigan had increased IgG antibody activity against the city water supply when compared with another patient from a different city and a control subject. Both of the latter lived in cities with water supplied from Lake Michigan. Two of the 5 patients showed definite inhibition by concentrated tap water (TW) of IgG antibody against HW. The source of antigens in water was not determined but must be considered in cases of this type of hypersensitivity pneumonitis. A sixth case consistent with humidifier disease had Cephalosporium cultured from her HW. On gel diffusion there was a band of identity with her serum against Cephalosporium extract and her own HW, and by radioimmunoassay (RIA) there was over 50% inhibition of her IgG antibody activity against HW by Cephalosporium. No antibody against her city TW was demonstrated.

Hypersensitivity pneumonitis and extrinsic asthma. An unusual association

A farmer who had no prior history of pulmonary disease developed tightness in the chest of rapid onset, shortness of breath, fever, and pulmonary infiltration while farming. The symptoms of his disease worsened with repeated exposure to the dusty farm field but remitted after each of five hospitalizations. Provocative challenge with inhalation of a water-soluble extract of dust from the field reproduced both asthmatic and pneumonitic features of the disease, while administration of corticosteroids clinically controlled the entire process. The data suggest a common cause for asthma and pneumonitis in this patient.

The contemporary concept of alveolitis

The concept of alveolitis as an exudative reaction dominated by plasma and cell accumulation within alveolar air spaces is reappraised in the light of new data concerning the reactional dynamics challenged by non-immune and immune agents vehiculated by air and blood ways, of the systemic approach of lung processes, of the consideration of alveolar walls and the air space delimited by them as a whole. The participation of alveolar mesenchymal cells and of blood cells and plasma in the development of alveolitis is obvious and the changes of alveolar walls are morphogenetically prevailing in time and space over those of air spaces, whose reactions represent only a secondary phase of the lung response. Both the primary parietoalveolar phase and the secondary air space phase form a whole reactional modality of the lung in which accumulative and proliferative, exudation and mobilization changes are highly interacting in the building up of alveolitis. The involved immune mechanisms may determine special cell accumulations, but the basic mechanism, the stereotype and the sequences of this reactional modality of the lung are not essentially different from the non-immune alveolar reactions.

On respirable organic antigens, mattresses and some idiopathic lung diseases

In surveying the environment of workers in a mattress factory thermophilic actinomycetes as well as phycomycetes and aspergillus species were isolated readily from work room dust, finished bat, sissal and the interior of baled linters. Those persons working with cotton products were shown to have a heavy, daily exposure to organisms known to be implicated in the pathogenesis of hypersensitivity pneumonitis. The authors suggest that further study of the inhaled antigens to which cotton workers are exposed is indicated before discarding immunologic mechanisms to explain the development of byssinosis and other pulmonary disorders to which such workers are subject.