Biological and immunological properties of Sugi basic protein-pullulan conjugate. I. Suppressive effect on IgE antibody production and on IgE-mediated reactions.

Sugi basic protein (SBP), a major allergen of Japanese cedar pollen, conjugated to pullulan acquires suppressive activities for IgE, but not for IgG antibody production, and for IgE-mediated PK reactions in a SBP-specific manner. When either normal or IgE anti-SBP antibody-producing mice were treated with the conjugate, IgE anti-SBP antibody levels scarcely increased even after immunization with SBP + alum. This suppression was shown to be SBP specific and IgE selective. The ability of SBP-pullulan conjugate to elicit PK reactions on passively sensitized rat skin was markedly reduced. Furthermore, the conjugate inhibited the reactions mediated by the IgE antibodies and native SBP when it was injected into the IgE antibody-sensitized sites 2 h prior to SBP challenge. The reduced ability of the conjugate to elicit PK reactions was not due to loss of antigenic determinants during the conjugation procedures because binding activity of the conjugate to anti-SBP antibodies was as strong as that of native SBP. These results indicate that SBP-pullulan conjugate may be useful for 'desensitization therapy' against the pollinosis.