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Abstract Background Hymenoptera venom immunotherapy (VIT) is a clinically effective treatment. However, little is known about its long-term clinical efficacy and biological effects. Several mechanisms have been proposed to account for VIT efficacy, including reduction of specific IgE and induction of allergen-specific IgG4, but the overall picture remains elusive. We investigated Vespula VIT clinical efficacy up to 8 years after discontinuation and the kinetics of Vespula-specific IgE and IgG4. Out of 686 consecutive patients we retrospectively selected and analysed a series of 23 patients with Vespula allergy that underwent a 5-year IT course, followed by a prolonged follow-up. Methods Clinical efficacy of VIT was assessed as number and severity of reactions to Vespula re-stinging events. The presence of Vespula-specific IgE and IgG4 was also monitored over time. Results During the VIT treatment, patients were protected, reporting no reactions or mild reactions in occasion of re-stinging events. This protection was entirely maintained during the follow-up, up to 8 years. Skin reactivity (reflecting mast cell-bound Vespula-specific IgE) and circulating Vespula-specific IgE levels declined substantially during VIT. Notably, this reduction was maintained over time during the follow-up. Moreover, all the patients were analysed for IgG4. A robust induction of Vespula-specific IgG4 was observed during the VIT course, with a substantial decline during the follow-up. Conclusions We conclude that Vespula VIT is a clinically effective treatment, which induces long-term protection after discontinuation. The reduction of specific IgE, assessed by skin tests and RAST, closely matches the VIT- induced protection, while the IgG4 induction seems not to be associated with VIT clinical efficacy in the long term.

Background: Hymenoptera venom immunotherapy (VIT) is a clinically effective treatment. However, little is known about its long-term clinical efficacy and biological effects. Several mechanisms have been proposed to account for VIT efficacy, including reduction of specific IgE and induction of allergen-specific IgG4, but the overall picture remains elusive. We investigated Vespula VIT clinical efficacy up to 8 years after discontinuation and the kinetics of Vespula-specific IgE and IgG4. Out of 686 consecutive patients we retrospectively selected and analysed a series of 23 patients with Vespula allergy that underwent a 5-year IT course, followed by a prolonged follow-up. Methods: Clinical efficacy of VIT was assessed as number and severity of reactions to Vespula re-stinging events. The presence of Vespula-specific IgE and IgG4 was also monitored over time. Results: During the VIT treatment, patients were protected, reporting no reactions or mild reactions in occasion of re-stinging events. This protection was entirely maintained during the follow-up, up to 8 years. Skin reactivity (reflecting mast cell-bound Vespula-specific IgE) and circulating Vespula-specific IgE levels declined substantially during VIT. Notably, this reduction was maintained over time during the follow-up. Moreover, all the patients were analysed for IgG4. A robust induction of Vespula-specific IgG4 was observed during the VIT course, with a substantial decline during the follow-up. Conclusions: We conclude that Vespula VIT is a clinically effective treatment, which induces long-term protection after discontinuation. The reduction of specific IgE, assessed by skin tests and RAST, closely matches the VIT- induced protection, while the IgG4 induction seems not to be associated with VIT clinical efficacy in the long term. [ABSTRACT FROM AUTHOR]

Background:: Forestry and field workers who work outdoors are at high risk for Hymenoptera stings and may develop occupation-related allergies from being stung. However, clinical and immunological surveys of Hymenoptera stings in the occupational setting have rarely been reported. We surveyed the natural history of Hymenoptera stings in Japanese forestry workers (FWs) and electrical facility field workers (EFFWs), and we assessed the utility of measuring specific (s)IgE Ab to Hymenptera venom. Methods:: Questionnaires on hornet and paper wasp stings were completed by 999 FWs, 354 EFFWs, and 365 office workers as controls between July and November 2009. Sera from these participants were tested for sIgE Ab levels to Hymenptera venom with a CAP system using a fluoroenzyme immunoassay. Results:: Of the participants who had experienced Hymenoptera stings, 914 (91.5%) were FWs, 293 (82.8%) were EFFWs, and 295 (80.8%) were controls. Of the participants who had experienced systemic reactions, 210 (21.0%) were FWs, 51 (14.4%) were EFFWs, and 39 (10.7%) were controls. sIgE Ab in response to hornet and wasp venom was positive (≥ class 2) in 42.4% and 41.4% of FWs, 30.1% and 31.4% of EFFWs, and 15.1% and 18.1% of controls, respectively. The likelihood of being sIgE-positive to wasp and hornet venom was significantly higher in FWs and EFFWs than in controls (P < 0.05). Conclusions:: 21% of FWs and 14% of EFFWs had experienced systemic reactions to Hymenoptera stings with a higher frequency compared with office workers in the same area. 40% of FWs and 30% of EFFWs had sera that were sIgE positive to Hymenoptera venom.

Pest-control operators represent a high occupational risk for Hymenoptera sting and a possibility of Hymenoptera allergic reactions, but the information is not well documented. A history of Hymenoptera stings was found in 118 (59.0%) of 200 Japanese pest-control operators. To evaluate the details of Hymenoptera stings and the factors associated with venom-specific IgE level which indicates Hymenoptera allergy, a questionnaire was administered and serum venom-specific IgE levels were measured in 105 subjects selected from 118 operators. The number of past stings was a mean of 3, and in most cases, they had been stung at only one site on the hand or the head and neck. Systemic reactions to Hymenoptera stings were also less frequent among them (5/105). Venom-specific IgE (to a yellow jacket, a wasp, and a honeybee) was measured by the CAP system, and it was found to be positive in 31.4% of the 105 subjects. The frequency of positive CAP was significantly associated with the following factors: the total serum IgE level (P<0.001), the time interval from the last sting-incident (P<0.001), the number of past stings (P<0.05), the most recent clinical symptoms (P<0.05), and an individual atopic history (P<0.05). Among these 5 factors, the former 4 factors were shown to influence the venom-specific IgE titer in the multiple-regression analysis using a forward-stepwise technique (multiple R=0.708, adjust R2=0.482, P<0.001). In particular, the influences of the total serum IgE level and the time interval were strong. These findings indicate that the frequency of Hymenoptera stings in pest-control operators is not as high as in beekeepers or forestry workers, and that venom-specific IgE is affected mainly by the total serum IgE level and the time interval from the last sting-incident. [ABSTRACT FROM AUTHOR]