Treatment of ragweed hay fever with urea-denatured antigen E

Urea-denatured antigen E (UDE) has lost the major determinants of antigen E (AgE), eliciting neither IgE nor IgG antibodies to native AgE in mice. UDE, however, stimulates T cells so that repeated injections result in specific but partial suppression of ongoing IgE responses to native AgE. An attempt was made to apply this property to the treatment of 10 ragweed-allergic human volunteers by repeated subcutaneous injections of UDE over about 18 mo. Local and systemic allergic reactions limited the dose to 4 to 75 microgram UDE per injection. Little or no antibody response to AgE was induced. Five patients had increased basophil sensitivity to UDE after 4 mo of injections. Five of eight patients who completed the study had evidence of suppression of IgE responses by exhibiting a 20% or less increase of IgE antibodies to ragweed on natural seasonal exposure. Three patients still exhibited this evidence at the next season of exposure 10 mo after the last injection. The two patients who received the lowest doses had greater than usual seasonal rises of IgE antibodies. There was no clinical evidence of improvement of hay fever symptoms. The results indicate that the immunologic properties of UDE in humans are similar to those in mice. The clinical applicability of these properties remains doubtful.