Clinical and in vitro studies on the role of immunotherapy in ragweed hay fever

Abstract The role of immunotherapy in ragweed hay fever has been investigated by a combination of clinical and laboratory technics. In the clinical study a course of immunization with the principal antigen of ragweed (antigen E) was compared to placebo injections in matched groups of patients. Double blind evaluation of the patient's symptoms was performed in a semiquantitative fashion by patient diary and physician examination. The laboratory study involved an in vitro model of human allergic reactions: the antigenically induced release of histamine from the isolated leukocytes of sensitive donors. This system allows an independent evaluation of cellular reactivity and the level of blocking antibodies, the latter measured by their ability to inhibit the in vitro allergic response. The sensitivity of an untreated donor's cells to ragweed antigen E correlated significantly (P Of eighteen pairs of treated and placebo patients, matched by cell sensitivity measurements, the treated partner had an appreciably lower symptom score in 10 pairs, there was little difference in 7 pairs and the untreated partner had a lower score in one pair (p