Effect of systemic and orally administered iota-carrageenan on ovalbumin-specific antibody response in the rat.

Iota-carrageenans are high molecular weight polygalactans commonly used in the food industry. Their immunomodulating effects were examined on the reaginic and IgG ovalbumin-specific responses after systemic or oral administration to Brown Norway rats. Intraperitoneal injection of ovalbumin with either iota-carrageenan or alum induced both a reaginic and IgG response. Reaginic antibodies were detected in the primary response with alum, but only in the secondary response with iota-carrageenan. Oral tolerance to ovalbumin was similarly induced whether the protein was given alone or admixed in solution with iota-carrageenan. These results confirmed the systemic adjuvant action of iota-carrageenan described earlier, and showed that this effect did not take place when orally administered.