Two Layers of Defense

Published on 
October 20, 2014

Every day, millions of particles from car exhaust, dirt, dust, pollen and tobacco smoke whirl in the air around us. While we inhale these unwanted microbes, how do we keep them out of our lungs? Two specialized cells in the airway play a major role.

Club cells are smooth, rounded cells that protect the inner lining (epithelium) of the airway by secreting several proteins. These proteins are able to digest or detoxify inhaled pollutants. Club cells are also stem cells, and they can divide and repair various areas of the bronchiolar epithelium.

Ciliated cells have tiny hairs (cilia), which sweep mucus up the airway where it can be coughed out or swallowed. Since the mucus traps larger particles, the ciliated cells help prevent these unwanted substances from entering the lungs and causing infection.

Image above: Club and ciliated cells from normal adult mouse airway (SEM 2800x)

Image credit: David Warburton, MD, and Gianluca Turcatel, PhD, from the Developmental Biology and Regenerative Medicine Program at The Saban Research Institute