MUC1 and hypersensitivity pneumonitis: However, in the study by Hant et al., the authors described that in patients with SSc-ILD without alveolitis (defined as a BAL fluid sample with ≥3% neutrophils, ≥2% eosinophils or both on a cell differential count, or any ground-glass opacity on HRCT), no correlation was observed between the KL-6 and SP-D levels and FVC% and TLCO% [19].