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Defensins and other antimicrobial peptides act in the innate host defense of epithelial surfaces. Human beta defensin 1 (hBD-1) has recently been shown to be expressed in airway epithelial cells and so has been implicated as a primary component of antibacterial activity in human lung. We attempted to purify these molecules from bronchoalveolar lavage fluid (BALF). Extraction of BALF on SepPak C-18 cartridges, followed by continuous acid-urea polyacrylamide gel electrophoresis and reverse-phase high-performance liquid chromatography yielded one fraction with antibacterial activity associated with factors of < 6.5 kD. N-terminal amino acid sequencing identified these peptides as human neutrophil defensins (HD) 1 through 3. No hBD-1 was detected. Together with lysozyme, it appears that HD-1 through -3 are the most prominent antimicrobial factors in BALF. The contribution of epithelial defensins such as hBD-1 to antibacterial defense of human airway in vivo remains to be elucidated.

Original publication




Journal article


Am J Respir Cell Mol Biol

Publication Date





352 - 356


Anti-Bacterial Agents, Blood Proteins, Bronchoalveolar Lavage Fluid, Chromatography, High Pressure Liquid, Defensins, Electrophoresis, Polyacrylamide Gel, Escherichia coli, Humans, Micrococcus, Muramidase, Neutrophils, Sequence Analysis, Sequence Homology, Amino Acid, beta-Defensins