In the CTD-ILD group, the concentration of KL-6 (r = 0.58, p = 0.04) and SP-D (r = 0.63, p = 0.02) correlated positively with the cell count in BAL, while a negative correlation was noted between KL-6 and the time from symptom onset (r = −0.51, p = 0.02). Here, MUC1 is linked to interstitial lung disease.