AIRWAY EPITHELIAL-CELLS ARE THE SITE OF EXPRESSION OF A MAMMALIAN ANTIMICROBIAL PEPTIDE GENE

We previously reported the isolation and characterization of a broad-s pectrum antimicrobial peptide from the bovine tracheal mucosa, which w e called tracheal antimicrobial peptide (TAP). We now show the TAP gen e is expressed throughout the adult conducting airway, from nasal to b ronchiolar tissue, but not in tissues other than airway mucosa, as det ermined by Northern blot analysis. In situ hybridization of airway sec tions localizes TAP mRNA to columnar cells of the pseudostratified epi thelium. We report the structural organization of the TAP gene and sho w that TAP is a member of a large family of related sequences with hig h nucleotide identity in the 5' exon. The data support the hypothesis that antimicrobial peptides contribute to host defense of the respirat ory tract.