Methods Of the 90 enrolled children with MPP, 30 cases were assigned as refractory MPP who failed to respond to at least 1-week treatment with macrolide antibiotics, while the other 60 cases were common MPP. A total of 30 children with congenital bronchial atresia or stenosis were included as controls. ELISA was used to assess BALF levels of IFN-γ, IL-4, IL-8 and TNF-α. RT-PCR was used to determine MP-DNA copy numbers in BALF.
ResultsCompared with the common MPP group, the refractory MPP group had a significantly higher MP-DNA copy number (3715352 ± 3162 vs. 2570 ± 5495; /ml; P<0.01). Children with refractory MPP achieved significantly increased BALF levels of IFN-γ, IL-8 and TNF-α than those with common MPP and the controls (40.55 ± 22.03 vs. 29.71 ± 11.18 vs. 27.54 ± 9.80; 213.58 ± 80.05 vs. 169.83 ± 83.56 vs. 79.50 ± 55.47; 240.90 ± 68.33 vs. 121.85 ± 63.15 vs. 101.33 ± 42.56; pg/ml; P<0.01). No significant difference in BALF levels of IL-4 was found among the three groups (23.00 ± 11.24 vs. 21.96 ± 11.94 vs. 17.61 ± 10.55; pg/ml; P>0.05).
Conclusion Refractory MPP may be associated with high MP load. Th1 mediated response may be dominant in the development of refractory MPP.