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. Author manuscript; available in PMC: 2017 Apr 1.
Published in final edited form as: Eur Respir J. 2016 Sep 1;48(4):1201–1214. doi: 10.1183/13993003.00120-2015

Figure 2. Mucin:leukocyte interactions during homeostasis and inflammation.

Figure 2

In healthy lungs, resident resting alveolar macrophages (AMs) are defensive and non-inflammatory. MUC5B from bronchioles mixes with alveolar fluids, providing a route for MUC5B to contact alveolar AMs. Homeostatic or low dose stimuli elicit defensive functions such as phagocytosis. During inflammation resident AMs can become activated, and this is associated with a decrease in their Siglec-F surface expression. In addition, leukocytes, such as monocyte-derived macrophages (which lack Siglec-F) or eosinophils (which express Siglec-F) are recruited and persist for brief periods of time. These transient populations are eliminated as inflammation resolves. In mice, resolution involves Siglec-F-mediated reductions in leukocyte activation and survival. Dampened and apoptotic cells are subsequently eliminated by MUC5B-mediated MCC.