Sarcoidosis is a complex multisystemic disease with a wide range of clinical manifestations. Its severity and evolution are highly variable and the prognostic utility of paraclinical markers is debated. We analysed the utility of the CD4/CD8 T-cell ratio (R) in bronchoalveolar lavage (BAL) fluid as a marker of sarcoidosis severity. We conducted an observational, retrospective, monocentric study involving patients with systemic sarcoidosis who underwent BAL for diagnostic purposes between June 2010 and April 2020. Among 62 patients, half had a CD4/CD8 T-cell ratio (R) value ≥ 3.5. Patients with R < 3.5 had more extrapulmonary manifestations, mainly abdominal (32.3% vs. 6.5%, p = 0.01) and tended to have a higher frequency of cardiac/central nervous system involvement (19.4% vs. 6.5%, p = 0.25). They also had more frequent interstitial lung involvement (80.6% vs. 67.7%, p = 0.2) and tended to have more severe respiratory impairment. The activation (p = 0.01) of CD8 + T cells in peripheral blood was significantly higher in patients with R < 3.5. By contrast, patients with R ≥ 3.5 tended to have more frequent musculoskeletal-cutaneous involvement (48.4% vs. 32.3%, p = 0.2). Treatment was initiated more frequently in patients with R < 3.5 (71% vs. 35.5%, p = 0.01), who also more frequently required immunosuppressive agents (54.5% vs. 36.4%, p = 0.02). An R value < 3.5 in BAL fluid has potential as a marker of sarcoidosis severity. Patients with a low R value had a worse prognosis with more severe respiratory impairment and more frequent multisystemic and extra-pulmonary involvement, and more frequently required immunosuppressive agents.< Leer menos