[T lymphocyte subsets in alveolar lavage and peripheral blood in sarcoidosis and extrinsic allergic alveolitis].

Accumulation of inflammatory and immune cells within lung parenchyma would constitute the initial step in producing the alveolar structural abnormalities. It is usually assumed that alveolitis, as assessed by broncho-alveolar lavage (BAL), represents a biological assessment of lung disease activity. The aim of this study, using monoclonal antibodies, is to characterize the T lymphocytes alveolitis in the lung and in peripheral blood in 3 well-defined populations: 1 degree) control subjects (n = 7); 2 degrees) patients with biopsy proven mediastino-pulmonary sarcoidosis (sarc) (n = 73), classified according to their clinical activity as active, inactive, chronic, and treated; 3 degrees) patients with extrinsic alveolar alveolitis (EAA) (n = 19). For the same BAL volume, the % of CD4+ cells and the CD4/CD8 ratio are increased in chronic and active sarc, contrasting with an increase in the % of CD8+ cells and a decrease in the CD4/CD8 ratio in the EAA. In absolute values, there are 2 times as many CD4+ cells and 5 times as many CD8+ cells in EAA than in sarcoidosis. In sarcoidosis, corticotherapy tends to normalize the CD4/CD8 ratio although the intensity of the lymphocytic alveolitis is not affected. In the peripheral blood, lymphopenia is observed only in the active form of sarc. in the CD4+ population, without any significant change in the CD4/CD8 ratio compared to the other groups. The number and distributions of BAL. T lymphocytes subsets may constitute a biological indicator for diagnostic orientation, but they do not distinguish sufficiently between the different groups of sarcoidosis to be of any prognostic value.