Sequential allergen desensitization of basophils is non-specific and may involve p38 MAPK.

BACKGROUND: Sequential allergen desensitization provides temporary tolerance for allergic patients. We adapted a clinical protocol to desensitize human blood basophils ex vivo and investigated the mechanism and allergen specificity. METHODS: We included 28 adult, grass allergic subjects. The optimal, activating allergen concentration was determined by measuring activated CD63(+) CD193(+) SS(Low) basophils in a basophil activation test with 8 log-dilutions of grass allergen. Basophils in whole blood were desensitized by incubation with twofold to 2.5-fold increasing allergen doses in 10 steps starting at 1 : 1000 of the optimal dose. Involvement of p38 mitogen-activated protein kinase (MAPK) was assessed after 3 min of allergen stimulation (n = 7). Allergen specificity was investigated by desensitizing cells from multi-allergic subjects with grass allergen and challenging with optimal doses of grass, birch, recombinant house dust mite (rDer p2) allergen or anti-IgE (n = 10). RESULTS: Desensitization reduced the fraction of blood basophils responding to challenge with an optimal allergen dose from a median (IQR) 81.0% (66.3-88.8) to 35.4% (19.8-47.1, P < 0.0001). CD63 MFI expression was reduced from 68 248 (29 336-92 001) to 30 496 (14 046-46 179, P < 0.0001). Basophils from multi-allergic subjects were desensitized with grass allergen. Challenge with grass allergen resulted in 39.6% activation (15.8-58.3). An unrelated challenge (birch, rDer p2 or anti-IgE) resulted in 53.4% activation (30.8-66.8, P = 0.16 compared with grass). Desensitization reduced p38 MAPK phosphorylation from a median 48.1% (15.6-92.8) to 26.1% (7.4-71.2, P = 0.047) and correlated with decrease in CD63 upregulation (n = 7, r > 0.79, P < 0.05). CONCLUSION: Desensitization attenuated basophil response rapidly and non-specifically at a stage before p38 MAPK phosphorylation.

The incidence of respiratory symptoms and sensitisation in baker apprentices.

The aim of the current study was to describe the incidence of respiratory symptoms and allergic sensitisation and the sequence of events leading to respiratory symptoms among Danish baker apprentices (BA). A total of 114 BA were surveyed over a 20-month period. Questionnaires were completed along with spirometric analysis and skin-prick tests to common and work-related allergens. Bronchial hyperresponsiveness (BHR) was determined at baseline and at the end of the follow-up period. The incidences of work-related rhinitis and asthma-like symptoms were 22.1 and 10.0 cases.100 person-yrs(-1), respectively. At 20 months the cumulative incidence proportion was 40.2 and 20.5% for rhinitis and asthma-like symptoms, respectively. The cumulative incidence of occupational sensitisation was 6.1%. An increased risk of asthma-like symptoms was found in both atopic subjects and in females. In the BA with new onset respiratory symptoms, an increase in BHR from baseline was observed. Forced expiratory volume in one second and forced vital capacity did not change during the follow-up period. No relationship was observed between new sensitisation and new symptoms. In conclusion rhinitis- and asthma-like symptoms were found to develop commonly in Danish baker apprentices. The mechanism by which symptoms arose was perceived to reflect the development of an inflammation rather than the production of a specific immunoglobulin E pathway, as sensitisation to occupational allergens was rarely observed. Hence, respiratory symptoms and allergy may develop through separate pathways.

Concentration-response relationship in imipramine treatment of diabetic neuropathy symptoms.

A single-blind imipramine dose titration study was conducted in 15 diabetic patients with neuropathy symptoms. The effect of treatment was evaluated by use of visual analog scales. Imipramine doses were individually adjusted until doses yielded plasma concentrations of imipramine plus desipramine that were well above 400 nmol/L or until all neuropathy symptoms had vanished. In all except one patient, there was marked relief of symptoms. In the responding patients (n = 14), much of the effect occurred at plasma levels of imipramine plus desipramine below 100 nmol/L, but a considerable interindividual variation was observed. Concentrations above 400 to 500 nmol/L were required to ensure maximal effect in all patients, and we did not find any indication of a decreased effect at high drug levels. The dose-dependent kinetics of imipramine was confirmed, and dose increments should therefore be carried out in small steps and preferably with monitoring of drug levels.

Lack of effect of mianserin on the symptoms of diabetic neuropathy.

The effect of the non-tricyclic antidepressant mianserin on symptoms of diabetic neuropathy has been studied in 18 patients in a double-blind, cross-over study with imipramine as a positive control. The patients were treated with placebo, mianserin, and imipramine, each for two weeks, in randomized order, with 1-3 weeks between the treatments. The symptoms were assessed by observer and self-rating scales. Mianserin was given in the fixed dosage of 60 mg per day, whereas the dose of imipramine was adjusted to yield the optimal plasma concentration of imipramine plus desipramine of 400-600 nmol.l-1. The mianserin plus desmethylmianserin plasma concentration ranged from 85 to 850 nmol.l-1, with the highest concentration in a patient who was a poor metabolizer of both sparteine and mephenytoin. The symptoms of neuropathy were significantly reduced during imipramine treatment, although somewhat less than in earlier studies. In contrast, mianserin produced no change in symptoms in comparison with placebo. As there was no evidence that higher mianserin (plus metabolite) steady-state concentrations were associated with a more favourable effect, the negative outcome appeared not to be related to underdosing with mianserin. In contrast to drugs with documented effects on the symptoms of diabetic neuropathy, mianserin has a very weak or no inhibitory effect on 5-HT and noradrenaline reuptake and this may explain its poor clinical effect.

Regulation of FcepsilonARI synthesis in human eosinophils.

FcepsilonRI, the high-affinity receptor for IgE, and eosinophils are thought to be key components of the allergic reaction underlying asthma and rhinitis. We provide evidence at the protein level that FcepsilonRI is expressed in human blood eosinophils, and that the synthesis of FcepsilonRI in purified human blood eosinophils is regulated by fibronectin in combination with IgE, IL-4, both involved in allergic reactions, and by RANTES, a strong chemotactic agent for eosinophils. This provides further evidence for a regulatory effect of IgE on human eosinophils in allergic disease.

Clomipramine vs desipramine vs placebo in the treatment of diabetic neuropathy symptoms. A double-blind cross-over study.

1. The effect of clomipramine and desipramine on diabetic neuropathy symptoms was examined in a double-blind, randomised, placebo controlled, cross-over study for 2 + 2 + 2 weeks. Drug doses were adjusted according to the sparteine phenotype, i.e. extensive metabolisers were treated with 75 mg clomipramine day-1 and 200 mg desipramine day-1 whereas poor metabolisers were treated with 50 mg day-1 of both drugs. Nineteen patients completed the study. 2. Plasma concentration of clomipramine plus desmethylclomipramine was 70-510 nM in extensive metabolisers, vs 590 and 750 nM in two poor metabolisers. Desipramine levels were 130-910 nM, vs 860 and 880 nM. 3. Both clomipramine and desipramine significantly reduced the symptoms of neuropathy as measured by observer- and self rating in comparison with placebo. Clomipramine tended to be more efficacious than desipramine. Patients with a weak or absent response on clomipramine had lower plasma concentrations (clomipramine plus desmethyl-clomipramine less than 200 nM) than patients with a better response. For desipramine a relationship between plasma concentration and effect was not established. 4. Side effect ratings did not differ for clomipramine and desipramine and on both drugs three patients withdrew due to side effects. 5. Compared with earlier results obtained with imipramine dosed on the basis of plasma level monitoring, clomipramine and desipramine on fixed doses appeared less efficacious whereas the side effect profiles were the same. At least for clomipramine, appropriate dose adjustment on the basis of plasma level monitoring may increase the efficacy.