Long-term Immunologic Effects of Broad-Spectrum Aeroallergen Immunotherapy

Abstract

Limb SL, Brown KC, Wood RA, Eggleston PA, Hamilton RG, Adkinson NF Jr. Int Arch Allergy Immunol. 2006;140:245–251 PURPOSE OF THE STUDY. To evaluate the long-term clinical effects, skin tests, and specific immunoglobulin E (IgE) levels from subjects who had previously received broad-spectrum aeroallergen immunotherapy several years earlier. STUDY POPULATION. Eighty-two polysensitized subjects who had previously been enrolled onto a randomized, double-blind, placebo-controlled trial of specific immunotherapy for treatment of childhood allergic asthma METHODS. Eighty-two subjects (78% male; mean age: 23 years) previously enrolled onto a randomized, placebo-controlled trial of immunotherapy for the treatment of childhood allergic asthma were reevaluated in adulthood (mean follow-up interval: 10.8 years) by puncture skin tests and CAP-RAST levels for major aeroallergens. All subjects originally completed at least 18 months (median: 27 months) of maintenance active immunotherapy treatment or placebo injections without subsequent immunotherapy. RESULTS. At adult follow-up, 36% of all skin tests to treatment allergens among subjects who received immunotherapy (n = 41) had significantly reduced intensity versus 26% of skin tests among placebo recipients (n = 41; P = .03). No significant differences were noted for individual treatment allergens. No significant differences were observed in the long-term changes of serum-specific IgE antibody levels for all or individual treatment allergens between immunotherapy treatment and placebo groups (P = .43). The treatment and placebo groups had a similar acquisition of new skin-test sensitivities from time of randomization in the original childhood trial to debriefing (15% vs 20%; P = .28) and to adult follow-up (30% vs 31%; P = .75). CONCLUSIONS. Immunotherapy suppresses skin-test sensitivity 8 to 16 years after discontinuation of treatment, but long-term effects on specific IgE levels in serum are not observed. Broad-spectrum immunotherapy does not seem to affect the acquisition of new inhalant sensitivities. REVIEWER COMMENTS. In this study, allergic-asthmatic children who participated in a double-blind, placebo-controlled immunotherapy trial were reevaluated as adults to determine if immunotherapy had long-lasting effects. This study revealed that asthmatic children who received immunotherapy to multiple allergens for a median of 27 months had limited long-term effects on the results of testing parameters routinely used in allergy practice. The long-term efficacy of immunotherapy and optimal duration of therapy are issues that remain open.