Since induced sputum has become a widely used non-invasive method of recovering cells from the surfaces of the bronchial airways, isolating specific cell populations will be necessary in order to learn more about their specific role in innate immunity and inflammation in the airways. Several studies have demonstrated the ability to conduct ex vivo analyses on sputum cells such as phagocytosis and surface marker measurements, but these have not been performed on isolated cell types.1–3 This study demonstrates the capability to isolate sputum macrophages from human volunteers in order to advance our understanding of macrophage biology in the airways. To this end, techniques that can enrich and isolate cells without significant activation would prove extremely useful. We compared two common methods for isolating and enriching macrophages in sputum: (1) magnetic bead separation; and (2) Percoll gel density gradient centrifugation. Cell purity and markers of cell activation (mRNA tumour necrosis factor α (TNFα)) …