ADJUVANT EFFECT OF PERTUSSIS TOXIN ON THE PRODUCTION OF ANTI-OVALBUMIN IGE IN MICE AND LACK OF DIRECT CORRELATION BETWEEN PCA AND ELISA

In studies designed to optimize the production and detection of anti-o valbumin (anti-Oa) IgE in Ham/ICR mice, a range of doses of both Oa an d pertussis toxin as the IgE adjuvant was explored. As determined by 4 8-hour passive cutaneous anaphylaxis (PCA) tests, the highest titre of anti-Oa IgE was obtained in a three-injection protocol with 0.1 mu g Oa and 1 mu g pertussis toxin for the priming dose, followed by two fu rther doses of 0.1 mu g Oa alone. In single-dose immunizations, the hi ghest PCA responses were obtained in sera from mice given 20 mu g Oa a nd 1 mu g pertussis toxin. These data confirm that murine IgE producti on to Oa depends on particular combinations of immunization variables. There was no direct correlation between the PCA and anti-IgE enzyme-l inked immunosorbent assay (ELISA) titres of the PCA-positive sera; ind eed there was a significant negative correlation. This relationship wa s not due to interference by IgG1, as there was no correlation between the anti-Oa IgG1 and anti-Oa IgE ELISA titres of the sera. These resu lts highlight the need for caution in assuming that serum IgE levels a s measured by ELISA will necessarily correlate positively with IgE bio logical activity as measured by allergen challenge in vivo.