Carrier-specific unresponsiveness in reaginic antibody formation. II. Suppression of hapten and carrier responsiveness in presensitized rats.

By inducing carrier-specific tolerance to sheep γ-globulin (SGG) in rats challenged with TNP-SGG in alum, it has been possible to study the effect of helper T-cell Unresponsiveness on IgE anti-TNP antibody formation. Rats primed to either the carrier (SGG) or the hapten (TNP as TNP-KLH) were treated with a single high dose (10 mg) of soluble SGG resulting in a suppression of both IgE anti-TNP and anti-SGG antibody which was maintained following a normally immunogenic secondary challenge with TNP-SGG in alum. This suppression was relatively long lasting, with no detectable IgE responsiveness to hapten or carrier observed for up to 8 weeks after tolerance induction. Suppressed animals were able to respond to the hapten when challenged with TNP-KLH, indicating that the induced effect did not directly involve the IgE antibody producing cells, but rather the carrier-specific helper cells. These results parallel our previous findings for IgM and IgG responses in a similar system. Such relatively long lasting and easily induced suppression in IgE antibody formation to specific protein antigens in primed animals may eventually provide a clinically useful means of allergic desensitization to large protein allergens.