Effect of allergenic structure on IgE levels in rats and mice

In outbred Lister hooded rats and inbred BALB/c mice, the IgE antibody response to CE induced in the presence of aluminum hydroxide adjuvant, is more difficult to suppress with high doses of antigen and/or frequent administration of antigen, than are such responses to DNP4.3-OA. Both types of IgE antibody were assayed by PCA in rats challenged with 1 mg of CE or DNP26-BSA. Unlike the rat system, anti-CE IgE responses could be induced in the BALB/c mouse in the absence of adjuvant. After a long course of weekly injections the IgE titer was the same (1 in 160) in all groups of mice given 6 ng to 630 micrograms/injection. The threshold sensitivity to CE of PCA induced by 1 in 5 dilutions of these sera ranged from 0.3 micrograms for sera from mice immunized with 6 ng per injection up to 10 micrograms for sera from mice immunized with 630 micrograms per injection. Only a small part of this difference in sensitivity could be accounted for by the presence of blocking antibody.