Immunologic response to administration of standardized dog allergen extract at differing doses

BackgroundThe immunologic response to immunotherapy with dog extract is not well characterized.ObjectiveThe purpose of this study was to examine the immunologic response to 3 doses of dog extract expressed as their Can f 1 content.MethodsCluster immunotherapy was administered to 28 patients with dog allergy who were randomly assigned to 1 of 4 treatment arms: placebo or acetone-precipitated extract containing 0.6 μg, 3.0 μg, or 15.0 μg Can f 1 per 0.5 mL maintenance dose. Studies included titrated skin prick tests, the late cutaneous response, titrated nasal challenge with dog extract, and serum allergen-specific IgE and IgG4. Dog allergen-stimulated lymphocyte proliferation was performed with measurement of secreted cytokines by ELISA and of intracellular cytokines by flow cytometry.ResultsThere was a significant dose-dependent response in suppression of titrated skin prick tests and suppression of the late cutaneous response. There was a significant increase from baseline in dog-specific IgG4 in both the high-dose and low-dose groups and a dose-dependent suppression of secreted TNF-α and increase in secreted TGF-β. There was a dose-dependent trend in suppression of secreted IL-4 with a significant decrease from baseline in the high-dose group. There were no significant changes in symptom scores; lymphocyte proliferation; secreted IFN-γ, IL-10, or IL-5; or intracellular cytokine production.ConclusionThe dose-response in immunologic parameters after immunotherapy with dog extract is similar to that previously demonstrated with cat extract.Clinical implicationsThe greatest and most consistent response is seen with a dose containing 15 μg Can f 1.