Iota-carrageenan induced reaginic antibody production in the rat--I. Characterisation and kinetics of the response.

The intraperitoneal injection of graded amounts of ovalbumin into inbred PVG strain rats was found to produce a dose dependent anti-ovalbumin antibody response without eliciting the production of ovalbumin-specific reaginic antibodies. The injection of ovalbumin admixed with iota-carrageenan enhanced the anti-ovalbumin response and simultaneously elicited the de novo production of reaginic anti-ovalbumin antibodies. Isotype analysis of the anti-sera revealed the presence of both IgG and IgE class anti-ovalbumin antibodies and demonstrated that non-reaginic IgE anti-ovalbumin antibodies were also a feature of this reaction. The reaginic antibody phase of the response, although transient in nature, was re-elicited by secondary antigen challenge. The administration of ovalbumin prior to the ovalbumin-carrageenan preparation was shown to abrogate the reaginic antibody response without significantly influencing the non-reaginic component of the response. Conversely the injection of iota-carrageenan prior to antigen, significantly suppressed the normal agglutinating anti-ovalbumin response but did not prevent the induction of reaginic antibodies. These observations demonstrate that iota-carrageenan can, under specific conditions, function as an efficient adjuvant, and is capable of by-passing the normal mechanisms responsible for controlling antigen specific reaginic antibody production.