Analysis of bronchoalveolar lavage cells and fluids in patients with hypersensitivity pneumonitis: possible role of chemotactic factors in the pathogenesis of disease

Immune responsiveness to inhaled antigens: local antibody production in the respiratory tract in health and lung diseases

The pulmonary defence mechanism in summer type hypersensitivity pneumonitis induced by Trichosporon cutaneum was investigated. We have studied the antibody response to fungal antigens in sera and bronchoalveolar lavage (BAL) fluids from patients with summer type hypersensitivity pneumonitis, bird fancier's lung, interstitial pneumonia associated with collagen vascular disease (INT-PNE), and from normal volunteers. Antigens extracted from fungi frequently isolated from home environments were used in ELISA to detect IgG and IgA antibodies in sera and BAL fluids. The results of the present study show that antibody titre in the respiratory tract to a variety of fungi from home environments is modulated by ongoing pulmonary inflammation, and that antibody production against inhaled antigens is altered by pulmonary inflammation resulting from diverse pathogenesis. This study concludes that the preexisting pulmonary inflammatory disease alters antibody production in the respiratory tract in response to inhaled fungi, and that the type of alteration depends in part on the etiology of the preexisting disease.

Activation of blood neutrophils in acute episodes of farmer's lung

Farmer's lung often presents clinically as recurring acute episodes several hours after exposure to moldy hay. During these episodes the blood neutrophil count increases. Because activated neutrophils release toxic oxygen metabolites and proteinases, we hypothesized that the pulmonary reaction in farmer's lung may be induced by the secretory products of activated neutrophils. To evaluate this concept, we quantified the respiratory burst of separated blood neutrophils from patients with farmer's lung (n = 12) during standardized exposure tests with moldy hay. The respiratory burst of these cells was evaluated by measuring zymosan-stimulated and lucigenin-amplified chemiluminescence (CL). Asymptomatic farmers (n = 12) and normal volunteers with no prior exposure to moldy hay (n = 15) were used as control subjects. As expected, following exposure in the group of patients with farmer's lung, striking changes in VC, TLCO, and PaO2 were observed, whereas there were only minor changes in these parameters in both control groups. In all three groups a considerable increase in the blood leukocyte count was observed. The CL response of the blood neutrophils from patients with farmer's lung 6 h after exposure was significantly higher than before or 1 h after exposure (p < 0.05 for both comparisons), whereas there was no significant change in the CL response in either control group during the observation period. Our results indicate that antigen inhalation induces an increase in the number of circulating neutrophils in patients and controls, but in patients with an acute episode of farmer's lung the neutrophils are primed for an enhanced respiratory burst and may thereby damage the lung.

Lung fibrosis in hypersensitivity pneumonitis. Association with CD4+ but not CD8+ cell dominant alveolitis and insidious onset

Seventeen cases of hypersensitivity pneumonitis (HP) at a symptomatic phase were categorized into two groups based on computed tomographic (CT) findings and histologic features of transbronchial lung biopsy specimens, HP accompanied by lung fibrosis (fibrosis group), and HP unaccompanied by lung fibrosis (nonfibrosis group). The fibrosis group comprised bird fancier's lung and HP of unknown etiology, whereas the nonfibrosis group mainly comprised summer-type HP. Comparison of results of pulmonary function tests between these two groups confirmed a restrictive impairment in the fibrosis group. Analyses of cellular components of bronchoalveolar lavage (BAL) fluids revealed lymphocytes, especially CD8+ T lymphocytes, were significantly increased in the nonfibrosis group in comparison with the fibrosis group, whereas CD4+ T cells were increased to the same level in the both groups. Analyses of the onset of disease showed that acute onset was observed mainly in nonfibrosis group and strongly correlated with increased CD8+ T lymphocytes in BAL fluids, while insidious onset was related to lung fibrosis and relatively increased CD4+ T lymphocytes in BAL fluids. These findings raise the possibility that highly elevated CD8+ T cells might have a protective effect on pulmonary fibrosis or that relatively increased CD4+ T cells might play an important role in the pathogenesis of pulmonary fibrosis of HP at the chronic phase.

Sequential changes in lung injury induced by preformed immune complexes

Immune complexes formed in the airside may be involved in the early parenchymal changes in hypersensitivity pneumonitis. The present study was undertaken to compare the responses of animals after an intratracheal injection with preformed immune complexes to those of patients with acute hypersensitivity pneumonitis, with special emphasis on sequential bronchoalveolar lavage findings and the possible role of chemotactic factors in the immune complex-induced lung injury. An increased number and percentage of polymorphonuclear cells could be detected in bronchoalveolar lavage fluids of guinea pigs within 48 hr following an intratracheal injection of preformed immune complexes. Chemotactic factor activity preceded the observed increase of polymorphonuclear cells in bronchoalveolar lavage fluids, suggesting a role for chemotactic factors in the sequestration of these cells in the lung. In addition, this study confirmed the usefulness of bronchoalveolar lavage in evaluating the pulmonary findings because the changes in bronchoalveolar lavage cell populations correlated with sequential histological findings. The sequential characteristics of the involved areas were noted to be of a peribronchial or bronchiolar infiltration with polymorphonuclear cells at early stages, then alveolar sac infiltration, followed by mild infiltration of mononuclear cells into the alveolar walls. The findings suggest a possible role for chemotactic factors in the accumulation of polymorphonuclear cells, and the sequential changes of bronchoalveolar lavage and histological findings in animals are comparable to those in patients with acute hypersensitivity pneumonitis.

Bronchoalveolar lavage T-cell and Ia antigen quantitation by flow cytometry in acute and chronic experimental hypersensitivity pneumonitis

Increasing evidence implicates effector T-cells in the pathogenesis of hypersensitivity pneumonitis. We utilized T-cell- and Ia-specific antibodies, flow cytometry, and computer analysis to quantitate T-cell numbers and Ia expression on lung cells of established rabbit models of acute and chronic hypersensitivity pneumonitis (HSP). We used analysis of variance (ANOVA) and Turkey's follow-up to evaluate group differences. In the acute HSP group, increased percentages of T-cells and greater Ia expression were present on bronchoalveolar lavage (BAL) cells at 24 h after inhalational allergen challenge. Increased BAL T-cell numbers were found in the chronic HSP group produced by repeated inhalation of antigen and muramyl dipeptide, compared to "desensitized" animals and control groups. Both chronic HSP and desensitized groups demonstrated increased Ia expression on BAL cells. Pathology scores for individual animals in both acute and chronic protocols correlated significantly (Pearson correlation coefficients) with total numbers of BAL cells, percentages of T-cells, and percentages of Ia-positive cells recovered. Findings are consistent with the hypothesis that cell-mediated hypersensitivity is a central mechanism in the pathogenesis of experimental hypersensitivity pneumonitis.