D. Vervloet

Altitude and house dust mites

The effects of altitude on house dust mites (one of the allergenic components of house dust) and the synthesis of anti-acari IgE antibodies were studied. Flotation extraction, counting, and identification of mites were performed each season for 1 yr on 218 mattress-dust samples taken from the Briancon region in the Alps, 900 to 3170 meters in altitude. Of the total dust samples, 41 were repeatedly positive and 177 repeatedly negative. The percentage of positive samples and the concentration of mites varied inversely with the altitude (40% positive with seven mites per 100 mg of dust at 900 to 1100 m, 14% and 4/100 mg at 1200 to 1350 m, 6% and 2/100 mg at 1400 to 1600 m, and 0% at higher altitudes). Species did not vary with altitude ( Dermatophagoides pteronyssinus 17%, Euroglyphus maynei 51%). In contrast, on the plain we found 80% of 77 dust samples positive (88 mites/100 mg of dust, 65% D. pteronyssinus ), with the peak in autumn. Total and specific IgE were measured initially and every 3 mo in 42 asthmatic children with positive skin tests to D. pteronyssinus and subjected to a 9-mo stay in Briancon (the highest city in Europe, 1365 m altitude). Geometric mean of initial total IgE (1047 U/ml) dropped to 40% (p≤0.001); specific IgE to D. pteronyssinus also fell. The value of climate change as a therapeutic modality in asthma is not supported by convincing data but may be attributed in some cases to removal of antigenic stimulation. The decrease in the number of mites and in IgE levels at higher altitudes supports this hypothesis.

Rapid Hymenoptera venom immunotherapy: comparative safety of three protocols

We compared 284 sting‐allergic patients treated with either a 4 day (group 1), 6 hr (group 2) or 210 min (group 3) rapid venom immunotherapy (RVIT) protocol using honey bee (HB) or yellow jacket (YJ) venom at cumulative doses of 527.6 μg, 226.6 μg and 101.1 μg respectively. The 4 day protocol involved four times as many injections as the 210 min protocol and twice as many as the 6 hr protocol. Desensitization was conducted in a hospital providing full emergency resuscitation facilities. In group 1, 1 × 100 μg boosters were given on days 7,10,15 and 45 and, in groups 2 and 3, 2 × 50 μg boosters were given on day 15 and 1 × 100 μg on day 45. The patients in the three groups were comparable with regard to clinical characteristics and immunological reactivity determined by skin tests. All patients had large local reactions. Systemic reactions (SR) occurred in 28.2% of patients in group 1, 28.6% in group 2 and 6.9% in group 3. The mean total cumulative venom dose (s.e.m.) for occurrence of SR was 123.75 (± 24.2) in group 1,183.27 (± 28.5) in group 2, and 36.43 (±9.3) in group 3. HB led to more systemic reactions than YJ venom. The rate of SR decreased when the cumulative venom dose was reduced during RVIT. The median dose was 137.6 μg in group 1, 226.6 μg in group 2, and 21.1 μg in group 3. No systemic reactions were observed after the booster injections. The results of this study suggest that short RVIT protocols with low cumulative doses carry a lesser risk of SR.

Anaphylactic reactions to muscle relaxants under general anesthesia

Eleven patients who suffered a reaction to the administration of muscle relaxants during induction of general anesthesia were explored using skin tests, leukocyte histamine release, lymphocyte transformation test, and the Prausnitz-Küstner test (P-K). Fifteen normal subjects served as controls. Patients who suffered a reaction showed considerable cutaneous hypersensitivity to muscle relaxants. Leukocyte histamine release was positive in three cases and the P-K test was positive in one case. These findings suggest possible specific serum IgE antibodies to muscle relaxants. However, reliable discrimination between immunological and idiosyncratic pharmacological mechanism is difficult to obtain.

Role of the quaternary ammonium ion determinants in allergy to muscle relaxants

Anaphylaxis to muscle relaxants appears to be a very useful model to study the IgE-dependent mechanisms of mediator release in humans. The serum IgE binding sites of the drugs appeared to be the ammonium ion determinants. In patients allergic to suxamethonium, one of the most frequently used muscle relaxants for general anesthesia, significant histamine release could be obtained in each case with simple diammonium salts. The length of the chain linking the ammonium groups appears to play an important role. In fact, when the length was less than or equal to 4 A, no significant histamine release could be obtained, whereas the optimal length for histamine release appeared to be greater than or equal to 6 A. Furthermore, muscle relaxants with a rigid backbone between the ammonium determinants (such as pancuronium) are less active than flexible molecules (such as suxamethonium) in initiating mediator release. This study suggests that small divalent molecules can induce anaphylactic shock in sensitized patients and that the length and the flexibility of the chain bearing the haptenic determinants appear to be important factors in the elicitation of mediator release.

Adverse reactions to suxamethonium and other muscle relaxants under general anestesia

Abstract The mechanisms of anaphylactic reactions to muscle relaxants under general anesthesia are not completely understood. Extending an earlier study, we report 41 cases of anaphylactic shock investigated by intradermal skin tests with muscle relaxants (suxamethonium, pancuronium, gallamine, nortoxiferine), in vitro leukocyte histamine release, and Prausnitz-Kustner tests. Intradermal tests were significantly positive at concentrations ranging from 10 to 10 5 times less than those in controls. Reproducibility tested for suxamethonium at a 1-year interval in five patients was good. Histamine release induced by muscle relaxants in Tris-albumin- Ca ++ -Mg ++ buffer showed positive results in 825 instances and was inhibited by antigen excess in seven cases. Addition of 50% deuterium oxide (D 2 0) caused significant increase of histamine release in positive cases and induced release in all five negative cases studied. Muscle relaxant-induced histamine release was inhibited by in vitro anti-IgE leukocyte desensitization. The mean maximal histamine release dropped from 58.2% ± 9.7 to 5.8% ± 2 (p

Hymenoptera ultra-rush venom immunotherapy (210 min): a safety study and risk factors.

Background In this study, which summarizes our last 5 years of experience, we evaluated the side‐effects of ultra‐rush venom immunotherapy and the possibility to define some risk factors for side‐effects as age, Hymenoptera venom used for treatment, treatment phase, severity of prior insect sting reaction, concentration of skin test positivity, and level of specific IgE.

A prospective national study of the safety of immunotherapy.

A prospective study was made in France to determine the frequency, nature, causes and consequences of systemic reactions occurring during specific immunotherapy. One hundred and fifty five reactions were recorded in 151, 997, injections given to 19,739 patients; a percentage of 0.1. It was higher with pollen extracts (0.2%) and practically nil with other extracts (house dust, Dermatophagoides, insect body, bacteria). Asthma, spasmodic rhinitis and urticaria were the most frequent, 80% of systemic reactions. In 59% no explanation could be found. The main known causes of adverse reactions were excessive doses of antigen, improper timing of treatment or incorrect technique of injection. After appropriate treatment the immunotherapy was continued in nearly 90% of the cases. Specific immunotherapy with the majority of extracts now being used, namely adsorbed extracts, is not dangerous but it must be precisely and cautiously done because errors are responsible for nearly 50% of the recorded systemic reactions.

Ultra-rush venom immunotherapy induces differential T cell activation and regulatory patterns according to the severity of allergy.

Background Venom immunotherapy (VIT) induces immune tolerance to hymenoptera venom antigens in allergic patients and is therefore a helpful model for studying modulation of allergic immune response. The objectives were to assess the early effects of ultra‐rush VIT on T lymphocyte activation and regulatory profile induction, in all subjects combined and according to the four severity grades of the Mueller classification.

Reliability of respiratory symptoms to diagnose atopy.

As reliance of responses to epidemiological questionnaires on atopic symptoms is doubtful, we studied the predictive value of these questions relative to atopy, defined by the presence of serum specific IgE, taking into account some extraneous variables such as age and sex. The study population included 2067 adults, 20‐60 years old. The protocol consisted of a standardized questionnaire and an evaluation of serum specific IgE using the Phadiatop® (Pharmacia Diagnostics, Uppsala, Sweden) test. The predictive value of each symptom suggestive of atopy was quite low, but was much dependent on age and sex. Women more often than men reported atopic symptoms in the absence of atopy. Similarly, the predictive value of each symptom decreased with age. Thus atopic symptoms do not have the same value as predictors of atopy. These findings have both clinical and epidemiological important implications.

Prevalence of latex sensitization in subjects attending health screening: implications for a perioperative screening

Background Because latex is a common allergen, the rate of latex sensitization may be high in the general population. A major issue would then be to detennine whether a systematic preoperative screening in the general population should be recommended.