The change of asthma-associated immunological parameters in children with Mycoplasma pneumoniae infection.

Background: Mycoplasma pneumoniae (M. pneumoniae), an atypical pathogen, is increasingly recognized as a common and important pathogen. Previous studies showed that M. pneumoniae infection may play a role in asthmatic mechanisms based on evidence collected from peripheral blood or sputum of patients or animal models. However, evidence reported from the airways of patients has been rare.

Objective: To estimate the role of M. pneumoniae infection in asthma by measuring the immunological parameters from peripheral blood and bronchoalveolar lavage fluid (BALF) in pediatric patients with mycoplasma pneumonia.

Methods: A total of 30 patients with mycoplasma pneumonia and 37 patients without M. pneumoniae infection undergoing fiberoptic bronchoscopy were reviewed. The peripheral blood cell count, immunoglobulins (Ig), BALF cell count, and other clinical and laboratory data were reviewed and analyzed.

Results: There were significantly more patients with raised basophil counts in the M. pneumoniae group than that in the control group (p = 0.033). Serum immunoglobulin (Ig) A, IgM, and IgG levels in the M. pneumoniae group were significantly higher than those in the control group (p = 0.008, p = 0.011, and p = 0.019, respectively). The percentage of eosinophils in BALF cells was in the range 0 to 10% in M. pneumoniae patients, while it ranged between 0 and 4% in the control group with a significant difference (p = 0.043). In the M. pneumoniae group, we found that the percentage of eosinophils in the BALF cells was positively correlated with age, the percentage of peripheral eosinophils, and BALF lymphocytes (r = 0.298, p = 0.030; r = 0.341, p = 0.014; r = 0.387, p = 0.006; respectively) and negatively correlated with total peripheral white blood cell (r = -0.387, p = 0.005).

Conclusion: These results suggest that M. pneumonia infection is associated with the asthma mechanism, especially in older children.