Calprotectin: An Ignored Biomarker of Neutrophilia in Pediatric Respiratory Diseases

Calprotectin (CP) is a non-covalent heterodimer formed by the subunits S100A8 (A8) and S100A9 (A9). When neutrophils become activated, undergo disruption, or die, this abundant cytosolic neutrophil protein is released. By fervently chelating trace metal ions that are essential for bacterial development, CP plays an important role in human innate immunity. It also serves as an alarmin by controlling the inflammatory response after it is released. Extracellular concentrations of CP increase in response to infection and inflammation, and are used as a biomarker of neutrophil activation in a variety of inflammatory diseases. Although it has been almost 40 years since CP was discovered, its use in daily pediatric practice is still limited. Current evidence suggests that CP could be used as a biomarker in a variety of pediatric respiratory diseases, and could become a valuable key factor in promoting diagnostic and therapeutic capacity. The aim of this study is to re-introduce CP to the medical community and to emphasize its potential role with the hope of integrating it as a useful adjunct, in the practice of pediatric respiratory medicine.

Automated summary

Calprotectin is a non-covalent heterodimer formed by S100A8 and S100A9 subunits, playing an important role in human innate immunity by chelating metal ions essential for bacterial development. It acts as an alarmin controlling the inflammatory response and can be used as a biomarker in inflammatory diseases, especially in pediatric respiratory diseases. Despite being discovered almost 40 years ago, its potential as a biomarker in various pediatric respiratory diseases is still underutilized.