Clinical and immunologic studies of rapid venom immunotherapy in Hymenoptera-sensitive patients.

A 2- to 5-hour regimen of rapid venom immunotherapy (RVIT) was administered to 33 patients with anaphylactic sensitivity to Hymenoptera venom in a hospital setting in which full emergency resuscitation equipment was available. The RVIT was administered as 10 increasing doses of each treatment venom every 10 to 15 minutes to achieve a final dose on day 1 of 58.55 micrograms per venom. Patients returned for booster venom injections of 60 micrograms on day 3, 70 micrograms on day 7, 80 micrograms on day 21, and 100 micrograms on day 35 after RVIT. Serial antigen-induced leukocyte histamine release studies were performed on day 1 in 10 patients before and after RVIT, as well as 3 1/2 months after initiation of RVIT. Of 33 patients, 32 achieved a cumulative venom dose on day 1 of at least 50 micrograms, and the entire group received a mean dose of 95.46 micrograms. Local reactions during RVIT occurred in 18 (55%) patients. Four patients (12%) experienced mild systemic reactions during or after completion of RVIT. Subsequent booster venom doses administered to 29 patients were well tolerated. A decrease in venom-induced leukocyte-histamine release from baseline was detected in three (30%) patients immediately after RVIT and in seven (70%) patients months after achieving maintenance doses. Cutaneous sensitivity decreased by at least one log10 concentration in eight (32%) of 25 patients. Twenty-two natural re-sting events occurred in 12 (50%) of 24 patients surveyed after successful completion of RVIT, of whom seven identified the insect as one for which they had been treated. No systemic reactions were reported. Results of this study indicate that RVIT is a safe, alternative method of venom administration for patients who are at immediate risk for re-sting anaphylactic episodes.