Issue 12/2025
Mileva, S.1, Kostova P.1, Hristova, Zh.2, Mladenova, M.3, Nencheva, D.1, Svinarov, D.2, Zlatareva, D.3, Petrova, G.1
1 University Hospital “Aleksandrovska”, Pediatrics Clinic – Sofia
2 University Hospital “Aleksandrovska”, Central Clinical Laboratory – Sofia
3 University Hospital “Aleksandrovska”, Diagnostic Imaging Clinic – Sofia
Calprotectin (CLP) has emerged as an important biomarker for the assessment of neutrophilic inflammation in children with cystic fibrosis (CF) and has significant diagnostic and prognostic potential. It is a heterodimeric complex of S100A8 and S100A9 – proteins of the S-100 family, which are involved in a number of key cellular processes: chemotaxis, migration, phosphorylation and regulation of cytoskeletal dynamics. Due to its small molecular mass, tissue diffusion and resistance to enzymatic degradation, CLP is a reliable marker of local and systemic neutrophil activation.
In CF, elevated CLP values in sputum reflect local inflammation in the respiratory tract, with concentrations varying according to age, genetic status and microbiological findings. High levels are associated with S. aureus and Serratia infection, the presence of ultrasound changes (atelectasis, interstitial changes) and more severe lung involvement. The data show a strong correlation between sputum CLP levels and clinical severity, and ROC analysis determines a cut-off of 133.73 mg/mL with high sensitivity for recognizing exacerbations.
Calprotectin is valuable both for early detection of exacerbations and for monitoring therapeutic response and predicting relapses. Combining it with clinical, imaging and microbiological indicators increases its diagnostic value.
Keywords: calprotectin, cystic fibrosis