Immunoglobulin E-suppressing and immunoglobulin G-enhancing tetanus toxoid prepared by conjugation with pullulan.

Immunoglobulin E (IgE) antibody response was found to be suppressed selectively and antigen specifically in mice given an antigen conjugated with pullulan, a linear copolymer of maltotriose, whereas IgM and IgG antibody responses were enhanced. On the basis of this finding, tetanus toxin was conjugated with pullulan by cyanuric chloride in the hope that the toxin would be detoxified by the conjugation procedure and could be used as an IgE-suppressing and IgG-enhancing toxoid without the aid of an aluminum adjuvant. This procedure of tetanus toxoid-pullulan conjugation apparently detoxified the toxin. Administration of the resulting tetanus toxoid, tetanus toxin-pullulan conjugate, to mice induced strong suppression of IgE antibody response with fairly good IgG response, whereas the alum-precipitated toxoid or plain toxoid, customarily used for vaccination, elicited high IgE antibody formation. The IgE antibody response was minimal, but the IgG antibody response was maximal in the conjugate-primed mice even after a booster injection with an IgE antibody-inducing dose of the alum-precipitated toxoid.