TSLP and chronic obstructive pulmonary disease: Similarly, Bal et al. showed in an inflammatory environment (i.e., lung tissues of patients with chronic obstructive pulmonary disease) that ILC2s can convert into IFNγ-producing ILC1s by exposure to either combination IL-1β and IL-12, IL-33, or TSLP (thymic stromal lymphopoietin) and IL-12 (31).