Determination of serum neutralizing antibodies reveals important difference in quality of antibodies against pertussis toxin in children after infection.

OBJECTIVES

To determine neutralizing antibodies to pertussis toxin (PTNAs) in children with suspected pertussis and to compare results of PTNAs and anti-PT IgG antibodies.

METHODS

172 hospitalized children with suspected pertussis were included. Pertussis was confirmed by culture, PCR and/or serology. PTNAs were determined by Chinese hamster ovary (CHO) cell assay.

RESULTS

A correlation between titers of PTNAs and anti-PT IgG levels was noticed in 172 patients (Spearman R = 0.68, P < 0.001). Subjects with same concentrations of anti-PT IgG antibodies could have different titers of PTNAs and the maximum difference observed reached to 1024 times in ELISA-confirmed patients. Moreover, subjects with same titers of PTNAs could have different concentrations of anti-PT IgG antibodies.

CONCLUSIONS

Our results indicated that in some children high concentrations of anti-PT IgG antibodies do not always mean effective PTNAs induced after infection, stressing the importance of detecting PTNAs after infection and vaccination. Clinical trial registry: Not applicable.