Significant correlation between symptom score and IgG4 antibody titer following long-term immunotherapy for perennial allergic rhinitis.

Although there is evidence of some measure of clinical benefit as well as immunologic change during the early phase of immunotherapy, a sustained clinical response is only possible with prolonged therapy. Immunotherapy has to be administered for about 3 to 5 years for such sustained clinical efficacy. This study aimed at investigating the dynamics of IgE and IgG4 antibodies after more than 5 years of immunotherapy, to examine the statistical correlation between these antibodies and symptom scores. Our study demonstrated that the allergen-specific IgE antibody level significantly decreases and the IgG4 antibody level significantly increases following immunotherapy. However, the percent decrease in IgE antibodies did not correlate with the percent decrease in symptom scores. On the other hand, the percent increase in IgG4 antibodies correlated with the percent decrease in symptom scores. We infer that an elevation of IgG4 antibodies is not simply an epiphenomenon unrelated to the underlying working mechanism of clinically successful immunotherapy, but probably makes an active contribution to symptom relief.