Down-regulation of IgE and IgG4 antibodies to tetanus toxoid and diphtheria toxoid by covaccination with cellular Bordetella pertussis vaccine.

Pertussis (P) toxin acts as adjuvant for IgE formation against simultaneously administered Ags in animal models. P vaccination may also have an adjuvant impact on IgE formation against coadministered diphtheria (D) and tetanus (T) Ags in humans. Sera of 103 D-T-P-immunized and 319 D-T-immunized children aged 2 years were analyzed for IgE, IgG4, and IgG to D and T (radioallergosorbent test), total IgE and IgE against common inhalant allergens (CAP radioallergosorbent test fluoroenzyme immunoassay). Fewer D-T-P- than D-T-immunized children had sera positive for T-IgE (12.6 vs 53.6%, p < 0.001), T-IgG4 (71.6 vs 89.2%, p < 0.001), D-IgE (31.0 vs 70.5%, p < 0.001), and D-IgG4 (85.2 vs 93.4%, p = 0.039). Suppression of T-IgE was not dependent on the cutoff chosen for a positive test result, but was dependent on the proportion of D-T immunizations given with P. The risk for sensitization to common environmental allergens did not differ (odds ratio 0.953, 95% confidence interval 0.815-1.114). No significant differences between D-T- and D-T-P-immunized children were found with regard to T-IgG or D-IgG. In summary, IgE and IgG4 (but not IgG) serum levels to coadministered D- and T-Ags are suppressed among P-immunized children as compared with nonimmunized children. These results suggest that the presence of a microbial product during Ag exposure can down-regulate an IgE/IgG4 response in humans.