Lectin Microarray Combined with Mass Spectrometry Identifies Haptoglobin‐Related Protein (HPR) as a Potential Serologic Biomarker for Separating Nonbacterial Pneumonia from Bacterial Pneumonia in Childhood

PURPOSE: Etiological diagnosis of pediatric patients with community-acquired pneumonia is difficult. For therapy, one of the major problems is the difficulty in separating bacterial pneumonia which would benefit from antibiotics from nonbacterial pneumonia. Therefore, to identify potential biomarkers for distinguishing nonbacterial pneumonia from bacterial pneumonia are sought . EXPERIMENTAL DESIGN: Lectin microarray containing 91 lectins is used to screen serums from pediatric patients with pneumonia. Lectin-based pull-down assay combined with LC-MS/MS is used to identify the potential biomarkers. RESULTS: SNA-I, a lectin binding preferentially to α2-6 linked sialic acid residues, shows higher binding signals (near 42 kDa) in the mycoplasma pneumonia group, when compared with the other groups. A total of 18 proteins are identified with LC-MS/MS. By western blot analysis, the authors confirm that the expression of haptoglobin-related protein (HPR) is elevated in pediatric patients with pneumonia compared with normal children (p < 0.001). Furthermore, HPR is higher in the mycoplasma pneumonia group (p < 0.01) and the viral pneumonia group (p < 0.05), when compared with the bacterial pneumonia group. CONCLUSIONS AND CLINICAL RELEVANCE: These results indicate that HPR is a potential serologic biomarker which can differentiate between bacterial pneumonia and nonbacterial pneumonia. Detection of serum HPR might be useful for clinical diagnosis.