TABLE 3.
IgE production after intranasal immunization with TT plus CT
| Expt no. | Serum sample | Total IgE (μg/ml) | PCA titera |
|---|---|---|---|
| 1 | Control (naive) | NDb | 0 |
| Immune | 2.20 | 90 | |
| 2 | Control | ND | 0 |
| Immune | 2.20 | 30 |
a
The PCA assay was used to compare the levels of TT-specific reagenic antibodies in these sera. Sera were serially diluted with PBS. A volume of 0.1 ml of each diluted sample was injected subcutaneously in the backs of F344 rats. Amounts of 1 ml of 1% Evan's blue and 200 μg of TT were injected intravenously the next day. The last dilution of sera with a positive reaction was considered the PCA titer. PCA reactivity was depleted by adsorption of sera with anti-IgE coated microbeads (data not shown).
b
ND, not detected. For total IgE assay, the detection limit was 250 ng/ml.