There were no statistically significant differences in SP-D (corrected or uncorrected) or phospholipid levels between the smokers with COPD and the smokers without COPD (Table 2 and Additional File 1: Supplemental Table S1); however, there was a correlation between FEV1% predicted and recovered BAL SP-D (R = 0.43; P < 0.05) among COPD subjects. Here, SFTPD is linked to chronic obstructive pulmonary disease.