Immunolocalization of CC10 in Clara cells in mouse and human lung

Two antisera, denoted R41 and R42, were raised against a synthetic peptide from the murine Clara cell-specific protein CC10, and one antiserum, denote d R40, was raised against human recombinant uteroglobin, the human homolog of murine CC10. Purified antigen-specific antisera, denoted R40AP, P41AP an d R42AP were prepared using peptide columns. The purified antisera were cha racterized by dot blots, immunohistochemistry, and immunoblots. Immunohisto chemistry of mouse lung showed specific labeling of Clara cells in distal b ronchioles by all three antisera. In human lung, the anti-uteroglobin antis erum specifically labeled Clara cells while the anti-mouse peptide antisera had weak crossreactivity and higher background staining. Electron microsco py revealed immunogold labeling of CC10 granules in Clara cells of mouse lu ng with all antisera. All antisera also labeled a 5-kDa protein on immunobl ots of mouse lung homogenates. The surface epithelium of the alveolar air s paces around the distal bronchioles were CC10 positive suggesting a functio nal activity for CC10 in the lung parenchyma distal to Clara cells. R40AP i mmunohistochemical staining of sections of normal human lungs and lungs fro m patients with surfactant protein B deficiency, bronchopneumonia, and idio pathic alveolar proteinosis illustrate the utility of the anti-human CC10 a ntibody for diagnostic pathology.