SPLUNC1 is increased in the small airways of CF lung. Immunohistochemical localisation of SPLUNC1 was performed as described in the materials and methods sections. Sections show submucosal gland staining in "normal" human airways (A) and a lack of staining in the epithelium of smaller airways (B, C, an enlarged inset of B). Expression of SPLUNC1 is increased in cases of CF (D-H) where staining was predominantly found in the epithelial cells of the smaller airways and also within the inflammatory cell containing mass within the plugged lumens. SPLUNC1 did not co-localise with MUC5AC (I). There was no staining within the peripheral lung tissue of cases of CF (J). Cases of emphysema (K) and bacterial pneumonia (L) also did not exhibit SPLUNC1 staining.