Sarcoidosis is a multisystem granulomatous inflammatory disorder, that predominantly involves the lungs. Patients with Löfgren's syndrome (LS) are characterized by acute onset and usually have the HLA-DRB1*03 (DR3^positive) allele and a good prognosis. Non-LS patients are usually DR3^negative and are more likely to develop chronic disease. The study aimed to identify bronchoalveolar lavage fluid (BALF) cells that could associate with disease severity (reduced pulmonary function tests (PFTs), advanced chest radiographs, need for treatment) and/or chronicity (duration >2 years) in newly diagnosed LS and non-LS patients, respectively.

We retrospectively included data from 955 non-LS patients, 477 LS patients, and 295 healthy controls (HC) in this study. Intra-group comparison of patients with resolving versus chronic disease was performed in LS and non-LS, respectively. Non-LS patients were divided into two subgroups according to the binary BALF cell concentrations for intra-group comparison (i.e. higher or lower than the 95th percentile of the BALF cells references in healthy individuals).

LS patients with a non-resolving disease course had higher BALF lymphocytes, neutrophils, and eosinophils than LS with a favourable outcome. In non-LS subjects increased BALF of the same cells and in addition also of basophils and mast cells were more likely associated with more severe disease course.

Increased BALF cells display prognostic significance in sarcoidosis. Certain BALF profiles should promote the clinician to monitor these patients more closely as they may associate non-resolving disease, in turn, resulting in future irreversible functional impairment.