Acute Pulmonary Inflammation Induced by Lung Overloading with Selenium Particles: Leukocyte Response and In Situ Detection of Selenium at High Resolution

Abstract

The kinetics of the acute inflammatory response of the lung was triggered in CD-1 mice by a single intratracheal instillation of a large amount of Se (10 mg); it was studied by quantitative cytology of bronchoalveolar lavage samples, light microscopy, and scanning electron microscopy coupled with x-ray elemental microanalysis. Bronchoalveolar lavage leukocytes were mostly neutrophils and increased from 12 to 24 h of Se treatment and decreased at 72 h. Only less than half of the granulocytes showed ingested Se particles; in contrast, virtually all BAL macrophages contained Se particles. Scanning electron microscopy coupled with X-ray elemental microanalysis revealed that the intracellular Se particles were heterogeneous in size (diameters from 0.4 and up to 14 μm), and that Se inclusions were sometimes accumulated at a pole of the cell. At 72 h after instillation of the particles, Se-loaded alveolar macrophages were migrated in the interstitial space of the alveoli. Se-positive regions had a focal distribution in the lung; accumulation of inflammatory cells erased the alveolar architecture of these areas of the deep lung. Our data indicates that Se overloading of the lung results in: (1) an acute inflammatory response that is dominated by neutrophils; (2) early removal of Se done mostly by alveolar macrophages, and (3) formation of focal areas of invasion of the lung parenchyma by inflammatory infiltrates.

The authors are very grateful to Professor Carlos M. Sá, director of CEMUP, for the use of his facilities and for his expertise. We thank Dr. Daniela Silva, Antonio Costa e Silva, Emanuel Monteiro, Madalena Costa, and Alexandrina Ribeiro for technical assistance. This work was supported in part by grants from Fundação Oriente and FCT Portugal.