CLDN10 and idiopathic pulmonary fibrosis: Cellular masses in the airspace containing Cldn10-positive cells were observed in all IPF sections tested (as shown in areas circled by dotted lines in Figure 2E, H & K) while 50% of the COPD sections tested (3 out of 6) displayed such a pathological finding (as shown in area circled by dotted line in Supplemental Figure S2A).