Bronchoalveolar Lavage in Occupational Lung Diseases

Abstract

Occupational lung diseases (OLDs) are related to the exposure and inhalation of organic, inorganic, and synthetic particles, fumes, gases, or infectious agents. From the long list of OLDs this article focuses the discussion on bronchoalveolar lavage (BAL) in parenchymal immunoinflammatory conditions, such as hypersensitivity pneumonitis (HP) and pneumoconiosis.Several antigens may cause HP, including products of plant or animal origin, aerosolized microorganisms, and organic chemicals. BAL is used not only to assess the pathogenesis of these diseases but also to identify the typical pattern of intense lymphocytic alveolitis, usually with a CD4:CD8 ratio below normal and frequently with the presence of mast cells, plasma cells, and foamy macrophages.Pneumoconioses are chronic interstitial lung diseases caused by the inhalation of mineral and metallic inorganic particles/dusts in an occupational setting, showing a decreasing prevalence in recent years.BAL is a useful tool not only to express the complex pathogenic mechanisms of these entities but also in excluding other diagnoses and causes of alveolitis, and to document specific exposures, such as the identification of asbestos bodies (ABs) in asbestosis or the proliferative response of BAL lymphocytes to beryllium in chronic beryllium disease (CBD).

Hypersensitivity pneumonitis

“…Lymphocytes usually appear within 24-48 h following the antigen sensitization (68) and their level remains increased for a long time after the cessation of antigen exposure, sometimes even for years. With cessation of exposure, their number however progressively decreases (69).…”

“…Recent studies suggest that this low CD4 + /CD8 + ratio is associated to the chronic form of HP and to asymptomatic individuals whereas a predominance of CD4 + T cells is related to the acute phase of the disease (67,68). In addition to the stage of the disease, the CD4 + /CD8 + ratio also depends on the type and dose of inhaled antigen as well as the duration of this antigenic exposure (3,68,69).…”

“…There are multiple determinants of HP. These include the type, intensity, and duration of exposure to the offending agent, antigen concentration and solubility, particles size, as well as host susceptibility (69).…”

“…The formation of the C5 fraction activates alveolar macrophages which release multiple inflammatory and chemotactic factors such as interleukin (IL)-8, RANTES, CCL18, MCP-1 and MIP-1a contributing to the recruitment of other cells such as neutrophils and macrophages in 4-6 h (93-107). Macrophages recovered from BAL of HP patients show a particular morphology characterized by a foamy cytoplasm (69). Mouse and human macrophages exposed to S. rectivirgula release, in vitro, tumour necrosis factor (TNF), IL-1 and IL-6 (108).…”

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“…Der lichtmikroskopische Nachweis von Asbestkörpern und Asbestfasern ist in der BAL möglich, weist aber lediglich auf die Exposition, nicht jedoch auf eine manifeste Erkrankung der Lungen hin [67]. Nach Vathesatogkit et al [68] und Cordeiro et al [69] stellt eine BAL die sensitivste Methode des Fasernachweises dar, wenn eine Lungenbiopsie nicht zur Verfügung steht. Ein negativer BAL-Befund schließt eine erhöhte Asbestbelastung im Lungengewebe nicht aus [69].…”