Notes: Background The aim of this study was to evaluate the in vivo and ex vivo effects of the H.-antagonist loratadine on histamine release. Methods The study was designed as a double-blind, crossover trial. Ten patients with allergic rhinitis due to Dermatophagoides pteronyssinus were treated with loratadine (10 mg daily p.o.) and with placebo for 1 week, with a 2-week interval between the two treatments. Nasal lavages with saline solution were done before and after challenge with the relevant allergen at the end of treatments with loratadine and placebo. Venous blood was taken after treatments, and basophil histamine release induced by anti-IgE (10 μg/ml), N-formyl-methionyl-leucyl-phenylalanine (fMLP, 1 μM). and Ca2+ ionophore A23187 (1 μM) was evaluated by ati automated fluorometric method. Results Treatment with loratadine attenuated early antigen-tnduced nasal obstruction, rhinorrhea. and itching. Nasal symptoms were accompanied by a significant histamine release in the nasal lavages collected 5 min after stimulation when the patients received placebo (median 4 ng/ml, range 1-28; P〈0.05). After treatment with loratadine, histamine release in the 5-min postchallenge lavages was almost abrogated (median 0.5 ng/ml, range 0-3; P〈0.01 vs placebo). Median anti-IgE-induced histamine release from basophils was 41.9% (range 27.8-79.2) after placebo and 30.0% (range 1.7-73.3, P 〈 0.05) after loratadine. Active treatment exerted an inhibitory effect also on basophil histamine release induced by fMLP and Ca2+ ionophore A23187. Conclusions Treatment for 1 week with loratadine reduces allergen-mduced nasal symptoms and inhibits in vivo and ex vivo histamine release in patients with allergic rhinitis.

Notes: The H1 antagonist loratadine has the capacity to inhibit histamine release from human basophils. The aim of this study was to investigate whether loratadine can also inhibit leukotriene C4 (LTC4) release from human leucocytes. Basophil-enriched mononuclear cell suspensions were prepared by centrifugation of peripheral venous blood (n= 10) on discontinuous Percoll gradients. Leucocytes were stimulated with anti-IgE, N-formylmethionyl-leucyl-phenylalanine (FMLP) and Ca2+ ionophore A23187; immunoreactive (i) LTC4 release in the cell supernatant was measured by a competitive radioimmunoassay and histamine release was evaluated by an automated fluorometric technique. Loratadine, in the concentration range of 1–50μM, exerted a dose-dependent inhibitory effect on IgE-mediated and IgE-independent histamine and iLTC4 release. The concentrations inhibiting 50% of histamine release were 30 μM (anti-IgE), 27μM (FMLP) and 19μM (Ca2+ ionophore A23187). The concentrations inhibiting 50% of iLTC4 release were 2–3 μM (anti-IgE). 11 μM (FMLP) and 1.7μM (Ca2+ ionophore A23187). The inhibitory activity on iLTC4 release was optimal after preincubation for 2h at 37°C, and was no longer evident when leucocytes were stimulated 2h after cell washing. Increased extracellular Ca2+ concentrations reduced the inhibitory activity of loratadine. These results indicate that loratadine has the capacity to inhibit the release of preformed and newly generated mediators from human basophil-enriched mononuclear cell suspensions.

Notes: The effects of different extracellular Na+ and CV2+ concentrations on histamine release from human basophils were investigated. Isosmotic replacement of extracellular Na + either with choline +, a non-permeant Na + analogue, or glucose significantly increased spontaneous and anti-IgE-induced histamine release. Basophils from 12 of 49 normal subjects, which were found not to release histamine upon challenge with an optimal dose of anti-IgE in a 135 mM NaCl buffer, were converted into releasing basophils when stimulation with anti-IgE was performed in a low-Na+ medium. The increase in Na + concentration in the extracellular medium was accompanied by a reduction in the magnitude of basophil response to anti-IgE, which was significantly more pronounced in non-releasers than in releasers (per cent inhibition by 70 mM NaCl 75.5 + 3.2 vs 43.5 + 9.0, P 〈 0.01). At higher Na+ concentrations a progressive and almost complete abrogation of histamine release was observed in non-releasers, but not in releasers (maximal per cent inhibition at 140 mM NaCl 97.3+1.3 vs 50.4 + 8.6). The Na+/H+ exchanger monensin had a dose-dependent inhibitory effect on anti-IgE-induced histamine release, and the concentration inhibiting 50% of histamine release was l.5 × 10−7M. When basophils were challenged in the presence of different Na+ and C2+ concentrations, it was shown that the two cations have antagonistic effects, which is to say that they down-regulate and upregulate histamine release, respectively. Moreover, the requirement of extracellular Ca2+ was lowered in a low-Na+ medium. These results suggest that Na+ and Ca+ ions contribute with opposite effects to the modulation of basophil response to anti-IgE and that non-releasing basophils are converted into releasing basophils in a low-Na + medium.

Notes: The response to anti-IgE serum of basophils from allergic and normal persons in the presence of whole plasma or as washed cells in Tyrode solution was examined to detect any inhibiting activity of human plasma. A factor reducing the potential of anti-IgE serum to degranulate basophils was present in plasma of normal but not of allergic persons. It is considered that this property of plasma could contribute to homeostatic control in immediate hypersensitivity.

Notes: Background Inflammatory alterations of respiratory airways have been found in patients with non-allergic asthma, but the triggering event has not been defined. An autoimmune activation of inflammatory cells has been hypothesized.Objective To evaluate whether histamine-releasing factors are present in sera from non-allergic asthmatics.Methods Twenty-four patients with non-allergic asthma underwent in vivo autologous serum skin test (ASST) and in vitro basophil histamine release assay using autologous basophils as well as basophils from normal donors. Twenty-seven subjects with respiratory allergy and three normal subjects were chosen as control.Results ASST was positive in 14/24 non-allergic asthmatics (58%) whereas it was negative in all 30 control subjects (P〈0.001). The serum of only one ASST-positive patient out of 12 (8.4%) induced in vitro histamine release from autologous basophils. The serum from another ASST-positive patient induced histamine release from membrane IgE-stripped autologous basophils. Sera from either non-allergic asthmatics or from control subjects did not provoke significant histamine release from basophils from three normal donors.Conclusion Skin reactivity to autologous serum is common among non-allergic asthmatics, indicating the presence of circulating histamine-releasing factors. However, only in a minority of patients in vitro functional evidence of histamine-releasing autoantibodies (anti-FcɛRI or anti-IgE) was obtained. The presence of circulating histamine-releasing factors might contribute to initiation/maintenance of inflammation in respiratory airways of non-allergic asthmatics.

Notes: In an unselected population of 133 young adults studied by prick testing to common allergens three groups were identified: eleven subjects with positive skin test responses and clinical symptoms of allergy; ten subjects only with positive skin tests and the remainder with negative skin tests.All subjects with positive skin tests (with and without symptoms) were studied by RAST on the serum and nasal secretions. Specific and non-specific bronchial provocation tests (BPT) were also carried out.The serum RAST was positive in all subjects with positive skin tests, and there was good correlation between high levels of circulating specific IgE and the presence of clinical symptoms.The RAST of nasal secretions was negative in most symptom-free subjects and as a diagnostic lest it was slightly better than the serum RAST.BPTs with extracts of the relevant allergens caused bronchospasm in every subject with a positive nasal secretion RAST. Only two subjects out of fifteen with a positive response were clinical asthmatics. Our results cast doubt on the clinical relevance of the BPT as it is usually conducted.

Notes: Background Allergy and asthma are typical disorders of the affluent societies. Migrants from developing to industrialized countries seem to be at increased risk of allergy and asthma development.Objective To evaluate time of onset, spectrum of sensitization and clinical features in a population of extra-European immigrants to Milan, Italy, complaining of allergy and asthma symptoms.Methods Data regarding 243 extra-European immigrants checked at an allergy clinic from 1994 to 2000 were collected retrospectively. The demographic data were compared with those of the extra-European immigrants living in Milan at the end of 1999.Results The patients were complaining of asthma (63.7%), rhinoconjunctivitis (56.7%), rhinitis alone (21%) or urticaria (3%). One hundred and eighty-seven out of 222 patients (84.3%) declared they were healthy before migrating and allergy/asthma symptoms started to appear after their arrival in Italy, namely after an average period of 4 years and 7 months. The proportion of male patients was lower than the proportion of men in the extra-European immigrant population (48% vs. 55%), suggesting that in adult immigrants allergy and asthma are more common in women than in men. Furthermore, there was an over-representation of Central-South Americans attending the clinic, which seemed to be due to a genetic predisposition to allergy/asthma development. When data were analysed for single countries, a trend towards an increased risk of allergy and asthma was found in immigrants from all Central-South American countries. A skin test positivity for at least one inhalant allergen was found in 196 out of 232 patients (81%), and the spectrum of allergic sensitization was similar to that of the Italian population living in the North of Italy.Conclusion Most extra-European immigrants declared that they were healthy at home and that allergy and asthma symptoms had appeared after immigration to Milan; lifestyle and environmental factors in a western industrialized city seem indeed to facilitate allergy/asthma onset in immigrants from developing countries. Allergy/asthma risk seems to be different in different ethnic groups.

Notes: The clinical use of RAST on the nasal secretions was investigated in seventeen atopic patients, with asthma or rhinitis, who had shown at a first diagnostic screening, some difficulties in the identification of the responsible allergen(s). The results of the skin tests, of the RAST on the serum and on the nasal secretions and of the specific provocation test (bronchial or nasal) were compared. In some cases the basophil degranulation test was performed. The results of the RAST on the nasal secretions were in perfect agreement with the provocation test. The skin tests and the RAST on the serum showed many discrepancies, particularly for Dermatophagoides, epidermal derivatives of cat and dog and moulds, and less frequently for Graminaceae and other pollens. It is concluded that RAST analysis on nasal secretions is useful in clinical diagnosis of allergy especially for Dermatophagoides, epidermal derivatives and moulds. Most false positive results were observed with the RAST on serum; in fifteen cases it was positive, while all the other tests, basophil degranulation test included, were negative. The data suggest that IgE may have a low affinity for basophil receptors.

Notes: Background Recently, distinct studies have shown that: (a) chronic idiopathic urticaria (CIU) is autoimmune in 30–50% of cases; (b) in patients with CIU the autologous serum skin test is inhibited by heparin; and (c) basophil histamine release induced in vitro by CIU sera maybe complement-dependent.Objective To carry out a comprehensive clinical and serological study on CIU based upon these observations.Methods Three hundred and six adults with CIU underwent intradermal (ID) test with autologous serum; 57 of them with autologous heparinized plasma as well. Sera from 121 patients (plasmas from 17) were employed to induce in vitro histamine release from basophils of normal donors. The effects of heating (56 °C, 60 min), filtration through membrane, and preincubation with heparin were evaluated as well.Results Autologous serum and plasma induced a weal and flare reaction in 205 out of 306 (205/306; 67%) and in 8/57 (14%) patients, respectively. Positive plasma skin tests were observed only in patients showing strongly positive serum skin tests. Plasma did not elicit any skin reaction in 3/3 patients with dermatographism who showed a positive intradermal test with saline. Sera from 20/121 (16.5%) patients induced significant histamine release from basophils of normal donors. 19/20 sera were from patients with a positive intradermal test; thus, basophil histamine release assay was positive in 19/87 (21.8%) patients with a positive serum skin test. Heating at 56 °C × 1 h markedly reduced the histamine-releasing activity of both serum and plasma from in vitro reactors. Ultrafiltered fractions 〉 100 kDa of both sera tested retained the histamine-releasing activity, whereas fractions 〈 100 kDa were not able to induce any histamine release. Heparin dose-dependently inhibited histamine release induced by sera and plasma, and by basophil agonists such as anti-IgE, formyl-methionyl-leucyl-phenilalanine, and interleukin (IL)-3.Conclusions 67% of our patients with CIU showed a positive autologous serum skin test. Sera from about 20% of those positive on autologous serum skin test induced histamine release from normal basophils in vitro probably as a consequence of the presence of functional autoantibodies. The marked difference between in vivo and in vitro findings could reflect the existence of a mast cell-specific histamine-releasing factor which does not release histamine from basophils of healthy blood donors. However, it might be also the result of in vivo priming of patients' cutaneous mast cells or of heterogeneity of basophil donors. At least in some cases complement seems essential for histamine-releasing activity of serum from patients with CIU. Heparin inhibits histamine release from both basophils (in vitro) and mast cells (in vivo), probably acting directly at a cellular level.