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Notes: The in vitro histamine release response of human intestinal mast cells and basophils challenged with anti-IgE, Concanavalin A, ionophore A23187 and food extracts was compared with skin prick test, RAST analysis and open food challenge. It was not possible to perform food challenge in all patients; however, seven children underwent open food challenge and in five the clinical diagnosis of “true” food allergy was confirmed. The intestinal mast cells were pooled from enzymatically dispersed duodenal biopsies obtained by duodenoscopy from 15 selected children suspected of food allergy, and five age-matched controls. In nine of 10 patients classified as “food allergic” intestinal mast cells released histamine to various food extracts in a dose-dependent fashion. From the mast cells of the nine food-allergic patients compared with non-allergics, the anti-IgE mediated mast cell histamine release was increased. Additionally, at 1000 U/ml anti-IgE the mast cell histamine release was increased compared with their corresponding basophils. However, in non-allergic subjects the histamine release of basophils was increased compared with their corresponding mast cells. Histamine release from basophils was positively correlated to the test scores of the RAST analysis, skin prick test, and food challenge. No apparent correlation between tests scores obtained from histamine release of intestinal mast cell and the other tests was demonstrated, except in children with diarrhoea as only symptom. However, the study gives evidence that duodenal mast cells actually are sensitized with specific IgE and thus may play a pathophysiological role in food hypersensitivity. In addition, the study shows that the ability of different stimuli, including food extracts, to trigger basophil histamine release does not correlate with their potency to induce histamine release from mast cells.

Notes: The interrelation of in vitro IgE-mediated parameters, i.e. serum-specific IgE (RAST), basophil cell-bound specific IgE, and histamine release from basophil leucocytes was investigated in a 1-year placebo-controlled, double-blind Cladosporium immunotherapy study involving 22 adult asthmatics. The intense and early burst (within 6 weeks of immunotherapy) of serum-specific IgE did not result in a corresponding increased binding of specific IgE molecules to basophils. Cell-bound IgE increased in the Cladosporium season in both groups at the same time as serum levels of specific IgE declined in the Cladosporium group. In the placebo group histamine release from circulating basophils paralleled changes in basophil-bound IgE. In Cladosporium-treated patients, histamine release cell sensitivity after a lag phase (during immunotherapy dose-increase) declined two log steps, i.e. the cells became less responding in spite of a significant increase in cell-bound IgE. To further evaluate the sensitizing capacity of circulating specific IgE, passive sensitization studies were performed using basophils from a single donor. Although sera taken at the maximal IgE-response showed an enhanced capacity of passive sensitization, the ratio between RAST and passive sensitization capacity increased significantly in Cladosporium-treated patients, implying a less than expected sensitization capacity of immunotherapy-induced specific IgE. The lack of active binding of IgE to basophils might be explained by a reduced Fc-affinity of immunotherapy-induced IgE in contrast to the Cladosporium seasonally induced IgE. Regarding the decrease in histamine release in Cladosporium-treated patients in spite of an increased amount of cell-bound specific IgE, immunotherapy may initiate a decrease in mediator releasibility which is not caused by a reduction in the number of Fc-receptors but rather some yet unknown subcellular mechanisms regulating the histamine release. The described changes in IgE-mediated parameters do not seem to be caused by interference with either specific IgG, or IgG4. Changes in histamine release in the Cladosporium, season were the only IgE-mediated parameter significantly related to the graded clinical efficacy of immunotherapy.

Notes: The inhibitory capacity of calcium antagonists on basophil histamine release was examined in allergic patients and in controls. All dihydropyridines tested (nifedipine, nimodipine, nitrendipine, nicardipine, felodipine) dose-dependently inhibited anti-IgE- and A23187-induced release with an order of potency of felodipine 〉 nicardipine 〉 nifedipine = nimodipine = nitrendipine. Only the inhibition induced by felodipine and nicardipine on anti-IgE-induced release could be counteracted by increasing extracellular calcium. Diltiazem, not belonging to the dihydropyridines, was a weak inhibitor. A combination of felodipine and verapamil in low concentrations exerted a synergistic inhibitory effect on histamine release, whereas this was not the case with other combinations of antagonists. The results suggest differences in the mode of action of the 1.4-dihydropyridines. This might be of significance in the search for calcium antagonists suitable in the treatment of allergic diseases.

Notes: Thirty-two cord blood samples were studied for histamine releasing capability by using a sensitive glass microfibre-based histamine analysis. Histamine was obtained after challenge with anti-IgE in 24 of the 32 samples. However, the net release in cord blood was only 25 % of that in adult blood and no relationship was found between histamine release response, total IgE in cord plasma, and a family history of atopic diseases. The low histamine release in cord blood seemed to be associated with the immunological IgE receptor complex activation and not with an immature basic cell function, since the calcium ionophore A23187 which bypasses the receptor complex induced identical histamine release curves in cord and adult blood. Furthermore, when comparing the results of passive sensitization of basophils from new-born and adult persons, the new-born basophils possessed a significant fraction of free IgE receptors, whereas in adults most of the receptors were occupied by IgE.

Notes: The histamine-releasing capability of lipopolysaccharides (LPS) was examined in human leukocyte suspensions. LPS alone did not release histamine, but was found to enhance the histamine release caused by anti-IgE. Also the IgE-mediated histamine release caused by specific antigens (allergens or bacteria) in sensitized individuals was enhanced by LPS. The potentiating effect of LPS was observed in grass pollen and dog dander allergic patients as well as in patients sensitized to E. coli or Staph, aureus bacteria. No potentiation was obtained by exposure to unspecific allergens or bacteria to which the persons were not sensitized. Bacteria can release histamine by immunological or nonimmunological mechanisms, and only the immunological histamine release was found to be potentiated by LPS. It is speculated that endotoxins reinforce release of histamine caused by allergens in allergic patients or by bacteria in persons sensitized to these microorganisms.

Notes: A case of monoclonal IgE type lambda with IgE levels about 1 mg/ml has been followed for 6 years. Except for a slight asthma no signs of malignancies, parasitic infestations or other known diseases compatible with hyper-IgE have been found. By the combination of fractional ammonium sulphate precipitation, gel filtration, chromatofocusing, and subtraction affinity chromatography the IgE protein was isolated in an immunochemically pure and homogeneous form. Immunofluorescence of bone marrow cells showed about 1 % IgE plasma cells. The amount of basophil bound IgE was 42 ng/106 cells, and histamine release from basophils challenged with anti-IgE was not different from that in atopic control persons, indicating a within-allergic-patients normal amount of IgE receptors. The protein-A reactivity was 0.4% equivalent to well-known IgE myeloma proteins. No antigen specificity of the IgE protein was found. Only a few cases of asymptomatic hyper-IgE are known, and it cannot be ruled out that this represents a premyeloma condition, since a similar case terminated in a malignant lymphoma.

Notes: Fifty asthmatics, candidates for hyposensitization with the house dust mite Dermatophagoides pteronyssinus (Dp), went through a series of allergy tests to evaluate the sensitivity of different organs to Dp. All patients were exposed to bronchial challenge with histamine and bronchial, nasal and conjunctival challenge with Dp, skin prick test (SPT) with Dp, analyses for Dp-specific histamine release from blood cells (HR) and for anti-Dp-IgE in serum (RAST). Results from 40 patients reacting positively in all tests were further analysed. Sensitivity to Dp in the various organs did not parallel, but a fair correlation was demonstrated between pulmonary allergen sensitivity and HR (r = 0.65, P 〈 0.001), and between pulmonary sensitivity to allergen and to histamine (r = 0.47, P 〈 0.001). Combined variations in HR and in (unspecific) bronchial sensitivity to histamine explained 53% of the variation in bronchial sensitivity to the allergen. This parameter showed less correlation to RAST and SPT (r = 0.31 and r = 0.35, P 〉 0.05). The results indicate that bronchial allergen challenge cannot be replaced by similar challenge of other organs, since the sensitivity of the mucosa in different organs of the same patient seems unrelated. Diagnosis should therefore be based on challenge of the organ with dominating clinical importance. In our selected group of patients, however, it was indicated that a substitution of the result of bronchial allergen challenge by measurement of unspecific bronchial reactivity, together with information on the general allergen sensitivity on a cellular level, might be possible. The unpleasant symptoms of the immediate and late bronchial reactions to allergen challenge could thereby be avoided.

Notes: Basophil histamine release was examined in 26 children suspected of having cow milk allergy (CMA). Following oral challenge with cow milk, the initial adverse reaction reappeared in 20 children, the majority developing urticaria. The urticaria patients showed a high degree of correlation between the results of histamine test, RAST and skin test. Children with gastrointestinal symptoms reacted to milk challenge, but only a few showed a positive histamine test, RAST and skin test. Among the patients with atopic dermatitis, the tests gave mostly negative results, which was in accordance with the lack of response to a milk challenge. The results obtained by removal from and fixation to the cell surface of IgE indicate an IgE-mediated reaction in CMA, which, in connection with the correlation between histamine test and RAST or skin lest, suggests basophil histamine release as a suitable method for testing Type I allergy in children suspected of CMA.

Notes: In a selected group of 60 house dust mite allergic asthmatics, the correlation between the bronchial sensitivity to house dust mite and effect parameters of mite-induced histamine release from washed blood cells was evaluated. Using a sensitive glass microfibre-based method, a significant positive correlation (r = 0.60; P 〈 0.001) was found between bronchial allergen sensitivity and basophil cell sensitivity expressed as the house dust mite concentration necessary to give half the maximum histamine release. No correlation was found between bronchial sensitivity and other parameters of the histamine release response. This way of determining the histamine release from washed blood cells is a simple and valuable alternative to bronchial allergen challenge.

Notes: Previous, plaeebo-controlled clinical trials with oral hyposensitization in grass pollinosis have been disappointing. Since the results possibly could be explained by too low doses of ingested allergens, the present study was initiated to evaluate the effect of high doses of allergens. Forty-two adults with symptoms in the grass pollen season and with grass pollen sensitivity demonstrated by skin prick test and conjunctival provocation test were included. Enterosoluble tablets were administered daily for 1 year. Twenty-two patients, who completed the study, received placebo and 17 mixed grass pollen allergens from rye grass, timothy grass, cultivated rye and velvet grass. Evaluated either by self-assessment or by symptom and medicine score before and after treatment, the group receiving pollens did not improve clinically compared the controls. During the study, conjunctival sensitivity decreased equally in the two groups, and changes in specific IgE, allergen-induced histamine release from blood cells and skin prick test were insignificant and with no difference between groups. Five patients, who received pollen allergens, had episodes of urticaria or angioedema, and a furter three patients on the same treatment had slight gastrointestinal side effects. In conclusion, enterosoluble grass pollen allergens in contrast to birch pollens did not have any therapeutic effect, even in doses more than 4,000 times higher than those used for subcutaneous hypersensitization. The reason may be degradation of allergens before the immune system is reached.