Basophil histamine release and airway response to mite allergen in atopic dermatitis.

Twelve patients with atopic dermatitis (AD) were subjected to in vitro histamine release from peripheral blood leukocytes (basophils) and in vivo bronchial inhalation challenge using house dust mite (Dermatophagoides farinae) allergen. Not only seven patients with asthmatic history but also five patients without asthma responded to both the in vitro and the in vivo challenges. A significant correlation was observed between HR30 (a mite concentration producing a 30% release of total cellular histamine) and PC20 allergen (a mite concentration producing a 20% fall in FEV1). There was also a significant correlation between MHR (maximal histamine release) and the maximal fall in FEV1. The relationship held for both AD patients with asthma and without asthma. These results suggest that histamine release induced by the house dust mite allergen is a good in vitro test for predicting the bronchial response to this allergen. They also suggest that these tests are not disease specific, but are valuable in evaluating the degree of atopic state in a subject.     

Bacterial antigens stimulate the production of histamine releasing factor (HRF) by lymphocytes from intrinsic asthmatic patients.

Lymphocyte from 12 intrinsic asthmatic patients and 10 healthy controls were studied for their capability to produce histamine releasing factor (HRF) in vitro. Spontaneous HRF production was measured by culturing the lymphocytes alone for 20 h. In another set of experiments lymphocytes were first preincubated separately with phytohaemagglutinin, antigens of Haemophilus influenzae, Streptococcus viridans, Staphylococcus sp. and Neisseria catarrhalis for 4 h then carefully washed three times and cultured alone for an additional 16 h. Cell-free supernatant was assayed for histamine releasing activity using basophils from healthy donors. It was observed that lymphocytes from intrinsic asthmatic patients spontaneously produced HRF. The production of this lymphokine was enhanced following preincubation of lymphocytes with phytohaemagglutinin or bacterial antigens. Results of skin test with bacterial antigens did not correlate with the magnitude of the production of HRF by lymphocytes. At gel chromatography over Sephadex G-75 bacterial antigen-stimulated lymphocyte supernatant revealed two peaks of HRF activity in the molecular weight ranges 35,000-50,000 and 3,000-7,000.     

Effects of infused histamine on asthmatic and normal subjects: comparison of skin test responses

The effect of histamine infused intravenously at sequentially increasing concentrations (0.05, 0.1, 0.25, 0.5, and 1 μ/kg/min) on the wheat responses to intradermal histamine and compound 48/80 in eight normal and five asthmatic subjects and to allergen skin tests in five asthmatic subjects was measured. These measurements were repeated following pretreatment with the H-1 antagonist hydroxyzine or the H-2 antagonist cimetidine, either alone or in combination. Histamine infused in progressively increasing concentrations had no effect on histamine, compound 48/80, or allergen skin tests either before or after H-1 or H-2 antihistamine treatment. No significant differene was found in the concentration of histamine or compound 48/80 required to elicit a 10-mm wheat in normal or asthmatic patients. Pretreatment with the H-2 antagonist alone had no effect on histamine or compound 48/80 skin tests in either group. However, the H-1 antagonist significantly reduced the wheat response to histamine (p < 0.05 normal; p < 0.025 asthmatics) and compound 48/80 (p < 0.05 normal; p < 0.025 asthmatics) in both groups. The combination of H-1 and H-2 histamine antagonists was not significantly different from the H-1 antagonist alone. Antigen skin testing was suppressed 82% by the hydroxyzine alone; no significant suppression was induced by cimetidine alone, and the combination of hydroxyzine plus cimetidine was only slightly more effective than hydroxyzine alone. The results indicate that blockade of histamine H-2 receptors with cimetidine has little or no additive effect on H-1 antagonist-suppressed skin test responses to histamine, compound , or antigen. Furthermore, the capacity of histamine to suppress histamine release in vitro from basophils was not demonstrated in vivo assessing skin mast cell responses. This observation combined with earlier studies on the human lung mast cell, which also failed to demonstrate that histamine had an inhibitory action, suggests that the human mast cell may not respond to histamine like the basophil and that this discrepancy may represent a fundamental difference in the cell types.     

Automated histamine analysis for in vitro allergy testing. II. Correlation of skin test results with in vitro whole blood histamine release in 82 patients.

The recently developed sensitive, automated histamine assay system was applied for in vitro allergy testing. The simplified method for histamine release from whole heparinized blood was used. Aliquots of blood and allergen were incubated for one hour at 37 degrees C, and each supernatant was then analyzed for histamine release. Nine common pollen and environmental allergens were used at three 10-fold dilutions for in vitro testing with the use of 20 ml of blood. Intradermal skin tests were correlated with the whole blood histamine release in 82 patients who had received no immunotherapy. A scoring system for the histamine results was developed to take into consideration the results with multiple allergen concentrations. When the skin test was strongly positive (greater than or equal to 3 + at 100 protein nitrogen units [PNU]/ml), the whole blood histamine release was positive in 89% of the tests. In contrast, when the skin test was negative ( less than 1 + at 100 PNU/ml), the histamine release was also negative in 99.8% of the cases. When the skin test was 1 +, the histamine release from whole blood was positive in 6% of the tests; and when the skin test was 2+, the whole blood results were positive in 32%. The accuracy, precision, and sensitivity of the automated histamine assay allow its application for the clinical study of allergic patients.     

Allergen- and anti-IgE-induced histamine release from whole blood

The release of histamine by allergen and anti-IgE from whole blood was observed in 34 asthmatic subjects with a positive skin test to house dust. The time course of histamine release showed that the release by allergen and anti-IgE peaked after 15 min incubation. There was no significant difference in the time course of the release from whole blood between allergen and anti-IgE. Anti-IgE-induced histamine release correlated to a certain extent with the serum IgE level. Histamine release by house dust, on the other hand, correlated with the radioallergosorbent test score. A striking difference was present in the dose-response slope between allergen and anti-IgE. The maximum percent release correlated with the dose-response slope by allergen, but not by anti-IgE. The amount of histamine release induced by anti-IgE paralleled the amount of the release by house dust in the cases sensitive to the allergen; less sensitive basophils to anti-IgE were less sensitive to house dust.     

A new glass microfibre-based histamine analysis for allergy testing in children

A new microfibre method for allergy testing measuring histamine release from human basophil leukocytes is described. Samples of 50 microliter washed blood are challenged with the suspected allergens. Released histamine is bound to microfibres and measured by a spectrofluorometrical method after removal of interfering substances by washing. The microfibre method (HR-MM) was compared to the conventional histamine release assay using the Ficoll-Hypaque gradient method (HR-FH) in 19 allergic children tested with one of three allergens. In addition, a comparison was made between the microfibre method and in vivo provocation tests, i.e. skin prick test (SPT), bronchial provocation test (BPT) and allergen specific serum IgE (RAST). It was found that the same individuals responded with histamine release to the same allergens in both histamine release assays, and the dose-response curves were almost identical. A positive correlation was found between the in vivo and in vitro tests. Thus it is concluded that the new method can provide reproducible, analytically precise (at the nanogram level) histamine release results in pediatric cases where: a positive SPT does not correlate with case history; BPT may be considered too hazardous or inconvenient; confirmation of negative or inconclusive SPT or RAST is needed. In contrast to other histamine release assays it is a convenient diagnostic tool in children since only small amounts of blood are needed and at least 96 tests can be carried out in 2 1/2 h.     

Chironomidae as a cause of IgE-mediated histamine release in patients with asthma

The present study was undertaken to assess the importance of Chironomidae as an allergen causing bronchial asthma in Japan, and to evaluate histamine release as an allergy test in chironomid-midge allergic patients. Extracts of Chironomidae (T. akamusi and C. Yoshimatsui) caused the release of histamine in six out of 13 allergic patients with positive skin tests. In contrast, histamine release induced by these allergens was not observed in leukocytes from two asthmatic patients and five control subjects without IgE antibody as evidenced by negative skin tests and RAST. There was a significant correlation between maximal histamine release and IgE antibody levels. Furthermore, a significant inverse relationship between the concentration of allergen causing 25% histamine release (HR25) and IgE antibody levels was observed. The correlation coefficients, however, between histamine release and RAST were not high, and there were discrepancies between the two tests in some cases. These results suggest that Chironomidae induce histamine release from leukocytes via IgE-mediated mechanism but histamine release cannot be replaced by RAST and also suggest that chironomid midge is one of the important allergens in Japan.     

IL-4 production by human basophils found in the lung following segmental allergen challenge

BACKGROUND: Human blood basophils secrete high levels of IL-4 following activation with specific allergen, yet their role as cytokine-producing cells in allergic lesions has not been described. OBJECTIVE: Our objective was to investigate whether and under what conditions basophils infiltrating allergic lesions in the lung secrete IL-4 in vitro. METHODS: Bronchoalveolar lavage (BAL) cells were recovered 20 hours after segmental allergen challenge. Basophils were enriched with Percoll using a protocol commonly used for blood basophils. IL-4 and histamine were measured in culture supernatants following activation with a variety of stimuli. Two-color flow cytometry was performed to detect intracellular IL-4. RESULTS: IL-4 protein was detected in all basophil culture supernatants following a 4- to 5-hour incubation in medium alone; the levels obtained did not significantly increase with the addition of anti-IgE. BAL basophils failed to release histamine in response to specific allergen but showed nearly 60% histamine release with N-formyl-methionyl-leucyl-phenylalanine, suggesting that they were desensitized to IgE-mediated stimuli as a result of their activation in vivo. Using these same conditions, IL-4 was not detected in BAL cell fractions enriched for lymphocytes and eosinophils. Ionomycin induced IL-4 secretion by BAL basophils, and this response was reduced with the addition of phorbol myristate acetate. In contrast, phorbol myristate acetate promoted the secretion of IL-4 by BAL cells enriched for lymphocytes; both findings are identical to those reported for basophils and lymphocytes purified from blood. Flow cytometry confirmed the secretion of IL-4 by BAL basophils. CONCLUSIONS: These data suggest that basophils migrating to the lung following allergen challenge represent a major source of IL-4.     

The late asthmatic response is associated with baseline allergen-specific proliferative responsiveness of peripheral T lymphocytes in vitro and serum interleukin-5

BACKGROUND: Increasing insights into the mechanism underlying the allergen-induced late asthmatic response (LAR) have been gained with implication of activated eosinophils and CD4+ T lymphocytes. However, the patient characteristics that indicate the individual capacity to develop a LAR are not well-defined. METHODS: In 22 subjects with mild to moderate house dust mite-allergic asthma, we investigated the relationship between the LAR and two other models of late-phase allergic inflammation, i.e. the allergen-specific proliferative response of peripheral blood T lymphocytes in vitro and the late cutaneous response. Non-specific bronchial responsiveness (PC20histamine), lung function (FEV1), peripheral blood eosinophil count, early phase allergic skin sensitivity, and levels of total and specific immunoglobulin E (IgE) were determined prior to bronchial allergen challenge. Serum levels of interleukin-5 (IL-5) were measured before and at several time points after allergen inhalation. RESULTS: A significant correlation was found between the magnitude of the LAR and the allergen-specific proliferative response of peripheral T lymphocytes (r = 0.44, P = 0.04) but not the late cutaneous response. Stepwise-multiple linear regression of the magnitude of the LAR on the parameters analysed at baseline, resulted in a model combining PC20 histamine, early phase allergic skin sensitivity, and the allergen-specific proliferative response of peripheral T lymphocytes (R2 = 0.84, P<0.001). No contribution of the late cutaneous response to the prediction of the LAR was found. Serum levels of IL-5 increased significantly at 6 h (P = 0.01) and 24 h (P = 0.003) after bronchial allergen challenge and correlated with the allergen-specific proliferative response of peripheral T lymphocytes in vitro (rho = 0.48, P = 0.02). CONCLUSIONS: The findings in this study point to a role of TH2-lymphocyte responses in the development of the allergen-induced LAR. In allergic asthmatic patients, allergen-specific responsiveness of peripheral T-lymphocytes in vitro may serve as a model to determine the individual capacity to develop a LAR after allergen inhalation.     

Histamine-Dependent Allergy Blood Test

Allergen-mediated histamine release from human leukocytes represents an important model for in vitro studies of allergic reactions. The purpose of this study was to determine whether the measurement of histamine released in allergic patients by radioenzymatic assay following mixing of their blood with common allergens represents a reliable index for diagnosis of atopic allergy. Three categories of allergens were used: 1) house dust and mite; 2) cat and dog dander; 3) trees, grasses and ragweed mixture. The presence of allergy was established by clinical history and intradermal skin testing in the study group of 150 patients. A significant allergen-mediated histamine release ranging from 4 to 65% of the total blood histamine content was observed in 96% of the patients with skin test sensitivity of greater than or equal to 3+. There was a significant correlation between skin testing and histamine release in terms of the allergens causing the response. Thus, the measurement of histamine by radioenzymatic technique following its release in blood in response to allergen challenge represents a clinically useful in vitro test for the diagnosis of atopic disease.     

Chronic urticaria: novel clinical and serological aspects

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 degrees 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 degrees C x 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.     

Bronchial allergen challenge in subjects with low levels of allergic sensitization to indoor allergens

BACKGROUND: Low skin reactivity to common inhalant allergens is frequently found in asymptomatic individuals as well as in patients with respiratory complaints. However, most studies on bronchial allergen challenge concern patients with high levels of allergic sensitization. The present study was directed to bronchial reactions after allergen challenge in subjects with low skin reactivity to Dermatophagoides pteronyssinus or cat dander. METHODS: Titrated intracutaneous skin tests, skin prick tests, specific IgE assays, histamine release on washed leukocytes, and bronchial histamine and allergen-challenge tests were performed in 20 subjects with an intracutaneous skin test threshold for cat dander (Felis domesticus) or D. pteronyssinus above 0.1 BU/ml (mean wheal diameter in skin prick test with 10000 BU/ml: 4.4mm). Ten of the 20 patients had specific IgE below the detection limit in at least one of the three IgE assays which were done. Fifteen patients had a specific IgE level below 2 kU/I in all three tests. As a positive control group, the same parameters were studied in seven moderately sensitized patients with an intracutaneous skin test threshold below 0.1 BU/ml (mean wheal diameter with 10000 BU/ml: 7.2mm). RESULTS: The 20 subjects with low levels of allergic sensitization had an early decrease in FEV1 of 8.6% (P<0.01) and a mean late decrease of 6.3% (P<0.05). There was a trend for decrease in PC20 histamine 24h after allergen challenge (-0.4 doubling doses, P=0.09). CONCLUSIONS: In this group of subjects with low levels of allergic sensitization, a statistically significant early and late decrease in FEV1 was found. However, the decrease in lung function was small and unnoticed by most patients. The increase in nonspecific bronchial hyperresponsiveness after bronchial allergen challenge did not reach statistical significance in the study group. The results indicate that allergen exposure in patients with low levels of allergic sensitization may lead to airways changes in the absence of acute symptoms.     

Skin Prick Testing and the Use of Histamine References

The skin prick test is a fundamental test in biological allergen standardization and in evaluation of changes in skin sensitivity due to treatment. The allergen concentration eliciting a wheal equal to that produced by histamine 1 mg/ml is generally accepted as the skin sensitivity. Using a standardized quantitative skin prick test, 25 mould allergic patients were tested with quadruplicate determinations of five 10-fold allergen concentrations of highly purified and standardized extracts. Histamine 1 and 10 mg/ml were used as positive references. The 10-fold increase of histamine resulted in a doubling of the histamine reaction and increased the mean wheal diameter from 4 to 7 mm. The correlation between skin sensitivity estimated by histamine 1 and 10 mg/ml is significant, but with a dissociation between the two ways of estimating the sensitivity of 0.25 log step in the low sensitivity range and 1.8 log step in the high sensitivity range (the difference at median sensitivity is 1 log step). No correlation was found between histamine- and allergen-induced wheal area increase, and the discrepancy might be caused by a difference in the endogenous histamine release and/or difference in the number of histamine receptors at different degrees of sensitivity. With the use of median values it is possible to perform biological standardization with histamine 10 mg/ml and interpolate to histamine 1 mg/ml. However, the response in individual patients varies, and because of the small wheal area and the low reproducibility with histamine 1 mg/ml we recommend the exchange of histamine 1 mg/ml to histamine 10 mg/ml as an international positive reference.     

The links between allergen skin test sensitivity, airway responsiveness and airway response to allergen

BACKGROUND: The allergen-induced early asthmatic response [provocation concentration (PC)20, the concentration causing a 20% forced expiratory volume in 1 s (FEV)1 fall] depends on the level of IgE sensitivity and the degree of nonallergic airway hyperresponsiveness (AHR) and can be predicted from histamine PC20 and allergen skin test endpoint. OBJECTIVES: We examined the relationships between allergen PC20, methacholine PC20, and allergen skin test endpoint and assessed the accuracy of both the histamine PC20-based prediction of allergen PC20 (using methacholine) and a new methacholine PC20-based prediction equation. METHODS: From 158 allergen challenges, the allergen PC20, the methacholine PC20, and the skin test endpoint were recorded and relationships between these three were sought. We compared the measured allergen PC20 to that predicted from the previous histamine PC20-based and the new methacholine-based formulae. RESULTS: In single regressions, allergen PC20 correlated with both methacholine PC20 (r=0.25, P=0.0015) and skin test endpoint (r=0.52, P <0.00005). The relationship was improved by multiple regression of log-allergen PC20vs. log-methacholine PC20 and log-endpoint (r=0.61, P <0.00005). The histamine-based formula predicted allergen PC20 to within 2 doubling concentrations in 80% and within 3 in 92%. The new methacholine-based formula to within 2 and 3 concentrations in 81% and 94%, respectively; only nine of 158 subjects were outside the 3 concentrations. CONCLUSIONS: We have confirmed the dependence of the allergen-induced early asthmatic response upon the level of allergic sensitivity and the degree of AHR, the latter as assessed by methacholine challenge. The allergen PC20 can be predicted to within 3 doubling concentrations in 94% of cases.     

Validated safety predictions of airway responses to house dust mite in asthma

BACKGROUND: House dust mite (HDM) is the most common aeroallergen causing sensitization in many Western countries and is often used in allergen inhalation challenges. The concentration of inhaled allergen causing an early asthmatic reaction [provocative concentration of inhaled allergen causing a 20% fall of forced expiratory volume in 1 s (FEV(1))(PC(20) allergen)] needs to be predicted for safety reasons to estimate accurately the severity of allergen-induced airway responsiveness. This can be accomplished by using the degree of non-specific airway responsiveness and skin sensitivity to allergen. OBJECTIVE: We derived prediction equations for HDM challenges using PC(20) histamine or PC(20) methacholine and skin sensitivity data obtained from patients with mild to moderate persistent asthma and validated these equations in an independent asthma population. METHODS: PC(20) histamine or PC(20) methacholine, skin sensitivity, and PC(20) allergen were collected retrospectively from 159 asthmatic patients participating in allergen challenge trials. Both the histamine and methacholine groups (n=75 and n=84, respectively), were divided randomly into a reference group to derive new equations to predict PC(20) allergen, and a validation group to test the new equations. RESULTS: Multiple linear regression analysis revealed that PC(20) allergen could be predicted either from PC(20) methacholine only ((10)log PC(20) allergen=-0.902+0.741.(10)log PC(20) methacholine) or from PC(20) histamine and skin sensitivity (SS) ((10)log PC(20) allergen=-0.494+0.231.(10)log SS+0.546.(10)log PC(20) histamine). In the validation study, these new equations accurately predicted PC(20) allergen following inhalation of HDM allergen allowing a safe starting concentration of allergen of three doubling concentrations below predicted PC(20) allergen in all cases. CONCLUSION: The early asthmatic response to inhaled HDM extract is predominantly determined by non-specific airway responsiveness to methacholine or histamine, whereas the influence of the cutaneous sensitivity to HDM appears to be rather limited. Our new equations accurately predict PC(20) allergen and hence are suitable for implementation in HDM inhalation studies.     

Histamine release from peripheral blood leukocytes with purified bee venom allergens: effect of hyperimmune beekeeper plasma

The response of 15 strongly bee-venom-allergic patients to highly purified venom allergens was compared using skin prick test titration, peripheral blood leukocyte (PBL) histamine release and radioallergosorbent test with three highly purified bee venom allergens: phospholipase (PLA2), hyaluronidase (HYAL) and acid phosphatase (ACID P). Sensitivity to the three allergens ranked in the same order for all three tests and in each case PLA2 was found to the most potent allergen. In the presence of hyperimmune beekeeper plasma, maximum histamine release was reduced significantly for all three allergens (p less than 0.001). Furthermore, hyperimmune beekeeper plasma increased the amount of allergen required for a comparable release of histamine (mean shift in dilution curve PLA2 917-fold; HYAL, 492-fold; ACID P, 61-fold). The release of histamine from whole blood was also compared with PBL + 10% normal human serum (NHS). For all three allergens maximum release was much lower from whole blood compared with washed cells + 10% NHS (p less than 0.001). These data confirm PLA2 as the major bee venom allergen by all three tests. Hyperimmune beekeeper plasma reduces maximum histamine release and increases its threshold. Histamine release in response to ACID P appears harder to block with hyperimmune beekeeper plasma than that provoked by PLA2 or HYAL (p less than 0.01). Whole blood releases less histamine and requires more allergen than washed cells, indicating that sensitivity of PBL in vivo is unlikely to be as great as washed PBL in vitro.     

Immediate and late phase allergic cutaneous reactions are not inducers of unspecific or specific local hyperreactivity

The present study evaluates the possibility of allergen-induced unspecific and specific dermal hyperreactivity with special reference to the presence of late cutaneous reactions and allergen-induced nasal hyperreactivity. Twenty-six patients with strictly seasonal allergic rhinitis participated. All had a positive skin prick test for birch (Betula verrucosa) and/or timothy (Phleum pratense). Ten patients had previously displayed an allergen-induced nasal hyperreactivity and six patients a late cutaneous reaction. An initial skin prick test with a relevant pollen allergen was done in triplicate. The immediate skin reactions were recorded after 15 min and any late-phase reaction after 6 h. Twenty-four hours later the patients were retested. The same pollen allergen was sited in the first flare reaction from the previous day. A histamine prick test was sited in the weal as well as in the third reaction from day 1. A histamine control was also performed in a previously unaffected area. The allergen-induced weal reactions decreased significantly at rechallenge compared with the results from the previous day (P less than 0.05). The histamine tests resulted in similar skin reactions regardless of whether or not they were done on a previous allergen test site. This was true for both specific and unspecific reactions when the subgroups of patients with previously demonstrated allergen-induced nasal hyperreactivity or late-phase skin reactions were evaluated separately. These results indicate that allergen-induced hyperreactivity is not a general feature of allergic inflammation but is a phenomenon restricted to specific sites, such as the airway mucosa.     

Basophil histamine release and lymphocyte proliferation tests in latex contact urticaria

Basophil histamine release and lymphocyte proliferation tests were examined with latex allergen prepared from surgical gloves in 15 patients with latex contact urticaria. The basophil histamine release test (BHRT) yielded positive results in 13/14 (93%) patients, whereas commercial latex RAST was positive in only 9/15 (60%) patients. Lymphocyte proliferation test (LPT) was positive in 3/15 (20%) patients, suggesting that cell-mediated immune reactions may also occur in latex allergy. However, patch tests to latex were negative and neither were epidermal Langerhans cells able to present latex antigen to T lymphocytes in vitro.     

Effect of autogenic bacterial antigens on the production of histamine releasing factor by mononuclear cells from intrinsic asthmatic patients

The production of histamine releasing factor (HRF) by mononuclear cells (MNC) from intrinsic asthmatic patients has previously been reported. In this study, we investigated the effect of preincubation of lymphocytes with autogenic killed bacteria upon the production of HRF. Bacteria were isolated from the sputum, and nasopharyngeal swab obtained from patients and control subjects. MNC from intrinsic asthmatics and healthy controls were preincubated with killed bacteria for 4 h, then washed and cultured for 18 h. HRF activity of the cell-free supernatants was assayed in the histamine release test using basophils from normal subjects. We found that MNC from the patients spontaneously produce significant amounts of HRF. Preincubation of the cells with autogenic bacterial antigens enhanced HRF production in 12 of 25 patients and only in one of 15 control subjects. No specific bacterial strain was identified as having the sole stimulatory property for HRF production; rather, individual susceptibility predisposes to the ability to produce HRF in response to some common bacteria. When MNC from healthy subjects were preincubated with bacterial antigens isolated from the patients, no enhancement in HRF production was observed. We concluded that MNC from some intrinsic asthmatics are specifically sensitized to certain bacterial antigens and release HRF upon contact with these antigens.     

Effect of terbutaline and bambuterol on immediate-type allergic skin responses and mediator release in human skin

Background: Beta-2 agonists are potent inhibitors of mast cell degranulation in vitro. Intradermally injected they also inhibit mast cell activation in human skin in vivo. To what extent orally administered ₂-agonists inhibit mast cell degranulation and allergic skin responses in vivo in daily recommended doses remains unclear.Purpose: The main purpose was to study the effects of oral administered terbutaline and bambuterol on allergen- and codeine-induced histamine release and skin responses in intact human skin in vivo. In addition, control studies were carried out with intradermally injected terbutaline.Methods: Ten allergic subjects were randomized to receive bambuterol (10 mg tablets twice daily), terbutaline (7.5 mg controlled release tablets twice daily) and corresponding placebo for 5 days with a washout phase of 3 days between treatments in a double-blind, double-dummy, cross-over trial. The patients were studied at the fifth day of each regimen, i.e. at day 5, 13, and 21. Allergen- and codeine-induced histamine release was measured by microdialysis technique. Wheal and flare reactions to allergen, codeine, and histamine were measured planimetrically. Measurements were performed in the morning on day 5 on each regimen before medication and for additional 5 h after administration of the morning dose. In a separate series of experiments in another 10 allergic patients, 1–1,000 nM (0.05–50 pmoles) of terbutaline was injected intradermally for measurement of histamine release, prostaglandin D2 (PGD2) synthesis and skin responses.Results: Neither orally administered terbutaline nor bambuterol significantly reduced allergen- or codeine-induced histamine release. Flare reactions to allergen, codeine and histamine remained unaffected which was also the case for the majority of the wheal reactions. In comparison, intradermally injected terbutaline significantly reduced allergen-induced histamine release, PGD₂ synthesis, and skin reactions. Codeine-induced histamine release remained unaffected. Terbutaline significantly reduced flare reactions to codeine and histamine with no effect on wheal reactions.Conclusions: Terbutaline, in micromolar concentrations, was a potent inhibitor of immediate allergic skin reactions primarily due to inhibition of mast cell degranulation. However orally administered terbutaline, as the active drug itself or released from its pro-drug bambuterol, did not inhibit mast cell activation or allergic skin responses. Received 28 January 2003; returned for revision 7 March 2003; accepted by M. Parnham 29 April 2003