FIG. 3.
The effect of intranasal immunization with CT on serum IgE levels (nanograms per milliliter). Mice were intranasally (i.n.) immunized weekly with 7.5 μg of influenza virus vaccine in combination with various doses of CT (0.1, 0.5, and 2.5 μg), including antigen alone (0 μg CT i.n.). One group of mice (i.p.) was intraperitoneally immunized with antigen but without CT. Sera were collected by retro-orbital bleeds at the indicated time points (days after intranasal immunization). The results are from sera collected from two experiments. Unimmunized mice (data not shown) had total serum IgE levels of ≤260 ng/ml.