A double-blind, placebo-controlled immunotherapy dose-response study with standardized cat extract

Changes in titrated skin prick test results. Shown are the changes in threshold of titrated skin prick tests to cat allergen extract from before immunotherapy to after the first maintenance injection. The overall dose effect is significant (P = .008), as are the changes with 3.0 μg (P = .02) and 15.0 μg (P = .002).

Increases from baseline to after the first maintenance injection in serum cat allergen–specific IgG₄. The overall dose effect is significant (P = .01), as are the changes with 3.0 μg (P = .01) and 15.0 μg (P = .006).

Changes from baseline to after the first maintenance injection in the percent of PBMCs positive for CD4 and IL-4 (by flow cytometry). The overall dose effect is significant (P = .03), as is the result with 15.0 μg (P = .003).