Asthma Susceptibility in Chlamydia-Infected Children Depends on Serum Protein

NEW YORK (Reuters Health) Nov 06 - An immune defense protein, known as mannose-binding lectin (MBL), plays a key role in determining asthma susceptibility in children infected with Chlamydia pneumoniae, new research suggests.

Several reports have linked C. pneumoniae infection with asthma. However, it remains unclear why only some children develop the respiratory condition, while others do not.

Recent findings suggest that MBL helps protect cells against infection with C. pneumoniae. Therefore, any variant MBL alleles could result in altered or deficient protein that is less effective in defending against the organism.

In the current study, Dr. Csaba Szalai, from Heim Pal Pediatric Hospital in Budapest, Hungary, and colleagues compared C. pneumonia infection in 139 asthmatic children and 174 healthy control subjects. In infected children, the researchers determined the MBL genotype.

The new findings are reported in the October issue of the Journal of Allergy and Clinical Immunology.

The percentage of children infected with C. pneumonia seemed to be comparable in both groups, the authors note.

However, among children with variant MBL alleles, a higher percentage in the asthmatic group had C. pneumonia antibodies than in the control group. Moreover, infected children with variant alleles were at higher risk for asthma than infected children with a normal MBL genotype. This risk was particularly high in subjects with chronic or recurrent infection.

"This is the first report illustrating an important association between MBL deficiency, C. pneumonia infection, and the development of asthma," the researchers state.

"If confirmed, these results suggest that genotyping individuals for MBL gene polymorphisms might be useful in predicting asthma risk in children infected with C. pneumoniae" and in identifying those more likely to benefit from antibiotic therapy, they add.

J Allergy Clin Immunol 2003;112:729-734.