IFNL1 and chronic obstructive pulmonary disease: We examined baseline sputum cell mRNA expression of type I and III IFNs and ISGs in 36 patients from the community-based COPD cohort and found that frequent exacerbators had significantly reduced sputum IFNβ and IFNλ2/3 mRNA expression with no difference in IFNλ1 (Fig. 1A).