Relationship between inflammatory processes and gas exchanges in pulmonary sarcoidosis.

In the present study, we investigated whether the analysis of cells and proteins collected by bronchoalveolar lavage (BAL) could accurately reflect the degree of functional impairment in pulmonary sarcoidosis. Eighteen patients with biopsy-proven sarcoidosis were prospectively evaluated. An inverse relationship was demonstrated between BAL coefficient of excretion relative to albumin (RCE) values of IgG and IgA and diffusion for carbon monoxide (Dco). A similar negative correlation existed with PaO2 at the end of a maximal exercise. Steroid therapy in five patients lowered concomitantly BAL RCE of IgA and IgG while Dco values increased. Immunoperoxidase studies in three lung biopsies revealed numerous Ig-containing cells within the lung parenchyma. We suggest that these BAL Ig values reflected the mononuclear cell infiltration of the bronchiolovascular sheaths and lung interstitium. This cellular infiltration likely induces a distortion of the capillary bed and may affect the gas exchanges in a reversible way.