Comparative ultrastructure and immunolabeling of MHC-II antigens of alveolar macrophages obtained from patients with paracoccidioidomycosis and other lung diseases.

Samples of alveolar macrophages (AM) obtained by bronchoalveolar lavage from patients with either paracoccidioidomycosis, silicosis, sarcoidosis, or allergic alveolitis were investigated by electron microscopy and immunocytochemistry to compare cellular ultrastructure and expression of MHC-II antigens in the AM cell surface. All samples of AM obtained from patients with these pathologies showed heterogeneous structural features. Although, this morphological diversity is also present in AM of healthy donors, our observations seem to indicate that in the diseases studied this morphofunctional diversity is associated with additional ultrastructural characteristics inherent to each disease. In paracoccidioidomycosis the proportion of vacuolated macrophages is significantly lower than in other diseases; this might indicate that in paracoccidioidomycosis the proportion of activated AM is smaller. We observed significant differences in the expression of MHC-II antigens. Silicosis, sarcoidosis, and allergic alveolitis do not differ significantly in the quantity of immunolabeled AM or in the distribution of the label. The percentage of AM from paracoccidioidomycosis that exhibit the MHC-II molecule is very low with poor immunolabeling. In this disease the low expression of the MHC-II molecule could be related to a decrease of the antigen presenting function by AM.