Sarcoidosis is a disorder of unknown origin, characterized by the formation of noncaseating epithelioid cell granulomas, probably antigen driven, most frequently occurring in the lungs. In addition to granuloma formation, there is often an extensive vascular disease as seen by the appearance of microangiopathies. Granuloma formation in the lungs is preceded by a mononuclear cell alveolitis with increased numbers of activated T lymphocytes and alveolar macrophages. Besides changes in T lymphocyte and alveolar macrophage populations, changes in the humoral immunity have been reported.
Clinical manifestations of sarcoidosis depend on the intensity of the inflammation and organ systems affected. In some sarcoidosis patients, the alveolitis remains subclinical, whereas in others both alveolitis and granuloma formation are present, resulting in specific pulmonary symptoms. Although the lung is the most frequently affected organ, extrapulmonary manifestations such as erythema nodosum commonly occur. Sleep apnea
Bronchoalveolar lavage (BAL) is regarded as an important diagnostic method in sarcoidosis. However, conflicting results have been reported in studies evaluating the utility of BAL in assessing the prognosis of the disease. The cellular profile in BAL fluid samples reflects the presence of alveolitis as a local expression of a disseminated immunologic disorder. Lymphocytes recovered in BAL fluid are predominantly T lymphocytes, and there is no more than a 5 percent proportion of В lymphocytes. Activation of alveolar T lymphocytes is a characteristic feature of sarcoidosis and is demonstrated not only by an increased expression of typical activation markers on the cell surface (immunophenotypic markers, such as HLA-DR antigen expression, T lymphocyte antigen receptor decrease and interleuldn-2 receptors), but also by the release of specific mediators (functional markers, such as IL-2, interferon gamma, and other T lymphocyte mediators). Moreover, activation of T lymphocytes in sarcoidosis is subset-specific. Also, inhibition of responsiveness of memory T lymphocytes to recall antigens is part of the immune response in active sarcoidosis, which has been suggested possibly to contribute to the anergy observed in these patients. According to current concepts, the process of cell-mediated immunity is thought to mediate the pathogenesis of sarcoidosis.
Studies on BAL fluid samples profile characteristics in sarcoidosis patients hitherto reported in literature give rise to conflicting data. These controversial results and disparity between conclusions may be explained by differences in the sarcoidosis subpopulations studied and methodologic variations, as well as the fact that sarcoidosis does not present as an entity. Only a few reports regarding the clinical presentation of the disease associated with alveolitis are available. Furthermore, many studies do not differentiate between smoker (Sm) and nonsmoker (NSm) patients.
The aim of this study was to investigate whether the way in which sarcoidosis presents is associated with differences in cellular profile in BAL fluid samples, especially with regard to the number of T lymphocytes and T lymphocyte subpopulations and the smoking status in sarcoidosis patients.