Immunotherapy: Parameters of assessment

Allergen immunotherapy has proved safe and effective for selected aeroallergens that can be studied under controlled conditions. Various mechanisms of action have been proposed with limited evidence for their role in the protection resulting from immunotherapy. The exception is blocking antibody, which was discovered 50 years ago. In eight successive studies sponsored or carried out by one institution in which clinical efficacy was demonstrated, the serum level of IgE antibody was unchanged or slightly increased. All eight studies showed a significant rise in the serum level of IgG antibody, and this response is the logical immunologic explanation for clinical efficacy. For aeroallergens that cannot be avoided or subjected to clinical efficacy studies, demonstrations of safety and of significant IgG antibody response constitute the appropriate method of assessment.